Wikibooks

Julia for MATLAB Users/Core Language/Language Fundamentals

< Julia for MATLAB Users

Language Fundamentals

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This page maps MATLAB functionality documented in the Language Fundamentals section of the MATLAB documentation to equivalent Julia (core language and/or package) functionality.

Another helpful resource is the noteworthy differences from MATLAB section of the Julia documentation.

Entering Commands

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Related: Julia REPL

ans Most recent answer
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Julia's ans is functionally basically identical, though note that it is available only at the REPL.

clc Clear Command Window
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Ctrl+L is nearly equivalent in the Julia REPL, though it does not erase history; you can still scroll up to see the history of the session. You can also equivalently (on Linux/Mac) run the clear(1) command in shell mode, i.e. ;+clear.

save Command Window text to file
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There doesn't appear to be an equivalent Julia REPL command.

format Set Command Window output display format
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There is no drop-in equivalent in the Julia REPL or IJulia for globally setting the output format.

home Send cursor home
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Ctrl+L is functionally equivalent in the Julia REPL.

iskeyword Determine whether input is MATLAB keyword
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There doesn't appear to be an equivalent Julia command, but see Keywords in the Julia manual.

more Control paged output for Command Window
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Matrices and Arrays

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See Multi-dimensional Arrays in the Julia Manual.

zeros Create array of all zeros; ones Create array of all ones
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Julia's zeros and ones are functionally equivalent. Note that the syntax for specifying the data type of the result is different, e.g. Julia: zeros(Int64, 3, 3) vs. MATLAB zeros(3,3, 'int64').

rand Uniformly distributed random numbers
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See Julia's rand.

true Logical 1 (true); false Logical 0 (false)
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eye Identity matrix
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In Julia to construct a numeric identity matrix, use something like Matrix(1.0I, 3, 3). Note that the symbol I is special in Julia; rather than representing a matrix, it is an instance of the UniformScaling operator so that in principle its use can be more efficient than the naive use of a dense matrix that happens to have 1's on the diagonal and zeros elsewhere.

diag Create diagonal matrix or get diagonal elements of matrix
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blkdiag Construct block diagonal matrix from input arguments
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cat Concatenate arrays along specified dimension
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horzcat Concatenate arrays horizontally
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See Julia's hcat function

vertcat Concatenate arrays vertically
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repelem Repeat copies of array elements
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repmat Repeat copies of array
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linspace Generate linearly spaced vector
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logspace Generate logarithmically spaced vector
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freqspace Frequency spacing for frequency response
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meshgrid 2-D and 3-D grids
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ndgrid Rectangular grid in N-D space
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length Length of largest array dimension
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Julia has a length function, however it does not operate the same way as Matlab's for multidimensional arrays. To get equivalent behavior to Matlab's length(X), use maximum(size(X)) in Julia.

size Array size
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ndims Number of array dimensions
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In Julia, ndims is similar but not identical. For instance, Julia does not ignore singleton dimensions.

numel Number of array elements
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In Julia, length is equivalent.

isscalar Determine whether input is scalar
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isvector Determine whether input is vector
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ismatrix Determine whether input is matrix
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isrow Determine whether input is row vector
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iscolumn Determine whether input is column vector
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isempty Determine whether array is empty
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sort Sort array elements
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sortrows Sort rows of matrix or table
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issorted Determine if array is sorted
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issortedrows Determine if matrix or table rows are sorted
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topkrows Top rows in sorted order
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flip Flip order of elements
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fliplr Flip array left to right
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flipud Flip array up to down
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rot90 Rotate array 90 degrees
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transpose Transpose vector or matrix
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ctranspose Complex conjugate transpose
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permute Rearrange dimensions of N-D array
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ipermute Inverse permute dimensions of N-D array
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circshift Shift array circularly
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shiftdim Shift dimensions
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reshape Reshape array
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squeeze Remove singleton dimensions
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Julia's dropdims function is similar though it requires the singleton dimension(s) to be specified explicitly.

colon Vector creation, array subscripting, and for-loop iteration
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end Terminate block of code, or indicate last array index
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Julia's end is basically equivalent.

ind2sub Subscripts from linear index
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sub2ind Convert subscripts to linear indices
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Operators and Elementary Operations

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See Mathematical Operations and Elementary Functions in the Julia manual.

Arithmetic

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plus Addition
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uplus Unary plus
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minus Subtraction
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uminus Unary minus
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times Element-wise multiplication
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rdivide Right array division
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ldivide Left array division
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power Element-wise power
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mtimes Matrix Multiplication
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mrdivide Solve systems of linear equations xA = B for x
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mldivide Solve systems of linear equations Ax = B for x
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mpower Matrix power
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cumprod Cumulative product
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cumsum Cumulative sum
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diff Differences and Approximate Derivatives
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movsum Moving sum
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prod Product of array elements
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sum Sum of array elements
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ceil Round toward positive infinity
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fix Round toward zero
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floor Round toward negative infinity
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idivide Integer division with rounding option
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mod Remainder after division (modulo operation)
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rem Remainder after division
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round Round to nearest decimal or integer
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bsxfun Apply element-wise operation to two arrays with implicit expansion enabled
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Relational Operations

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eq Determine equality
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ge Determine greater than or equal to
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gt Determine greater than
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le Determine less than or equal to
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lt Determine less than
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ne Determine inequality
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isequal Determine array equality
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isequaln Determine array equality, treating NaN values as equal
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Logical Operations

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Logical Operators: Short-circuit Logical operations with short-circuiting

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and Find logical AND
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not Find logical NOT
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or Find logical OR
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xor Find logical exclusive-OR
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all Determine if all array elements are nonzero or true
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any Determine if any array elements are nonzero
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false Logical 0 (false)
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find Find indices and values of nonzero elements
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In Julia, findall provides similar functionality. See also findfirst, findlast, findnext and findprev.

islogical Determine if input is logical array
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logical Convert numeric values to logicals
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true Logical 1 (true)
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Set Operations

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intersect Set intersection of two arrays

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ismember Array elements that are members of set array

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ismembertol Members of set within tolerance

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issorted Determine if array is sorted

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setdiff Set difference of two arrays

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setxor Set exclusive OR of two arrays

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union Set union of two arrays

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unique Unique values in array

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uniquetol Unique values within tolerance

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join Combine two tables or timetables by rows using key variables

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innerjoin Inner join between two tables or timetables

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outerjoin Outer join between two tables or timetables

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Bit-Wise Operations

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bitand Bit-wise AND

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bitcmp Bit-wise complement

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bitget Get bit at specified position

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bitor Bit-wise OR

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bitset Set bit at specific location

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bitshift Shift bits specified number of places

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bitxor Bit-wise XOR

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swapbytes Swap byte ordering

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Data Types

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See Types in the Julia manual.

Numeric Types

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double Double-precision arrays

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single Single-precision arrays

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int8 8-bit signed integer arrays

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int16 16-bit signed integer arrays

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int32 32-bit signed integer arrays

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int64 64-bit signed integer arrays

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uint8 8-bit unsigned integer arrays

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uint16 16-bit unsigned integer arrays

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uint32 32-bit unsigned integer arrays

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uint64 64-bit unsigned integer arrays

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cast Cast variable to different data type

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typecast Convert data types without changing underlying data

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isinteger Determine if input is integer array

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isfloat Determine if input is floating-point array

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isnumeric Determine if input is numeric array

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isreal Determine whether array is real

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isfinite Array elements that are finite

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isinf Array elements that are infinite

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isnan Array elements that are NaN

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eps Floating-point relative accuracy

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flintmax Largest consecutive integer in floating-point format

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Inf Infinity

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intmax Largest value of specified integer type

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intmin Smallest value of specified integer type

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NaN Not-a-Number

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realmax Largest positive floating-point number

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realmin Smallest positive normalized floating-point number

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Characters and Strings

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string String array

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strings Create array of strings with no characters

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join Combine strings

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char Character array

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cellstr Convert to cell array of character vectors

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blanks Create character array of blanks

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newline Create newline character

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compose Convert data into formatted string array

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sprintf Format data into string

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strcat Concatenate strings horizontally

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cOnverTcHarstostrings Convert character arrays to string arrays, leaving other arrays unaltered

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cOnvertsTrIngstoChars Convert string arrays to character arrays, leaving other arrays unaltered

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ischar Determine if input is character array

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iscellstr Determine if input is cell array of character vectors

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isstring Determine if input is string array

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isStringScalar Determine if input is string array with one element

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strlength Length of strings in string array

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isstrprop Determine if string is of specified category

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isletter Determine which characters are letters

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isspace Determine which characters are space characters

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contains Determine if pattern is in string

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count Count occurrences of pattern in string

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endsWith Determine if string ends with pattern

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StartsWith Determine if string starts with pattern

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strfind Find one string within another

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sscanf Read formatted data from string

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replace Find and replace substrings in string array

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rEplacebetween Replace substrings identified by indicators that mark their starts and ends

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strrep Find and replace substring

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join Combine strings

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split Split strings in string array

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splitlines Split string at newline characters

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strjoin Join text in array

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strsplit Split string at specified delimiter

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strtok Selected parts of string

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erase Delete substrings within strings

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erasebetween Delete substrings between indicators that mark starts and ends of substrings

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eXtractAfter Extract substring after specified position

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eXtractBefore Extract substring before specified position

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eXtractbetween Extract substrings between indicators that mark starts and ends of substrings

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InsertAfter Insert string after specified substring

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InsertBefore Insert string before specified substring

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pad Add leading or trailing characters to strings

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strip Remove leading and trailing characters from string

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lower Convert string to lowercase

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upper Convert string to uppercase

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reverse Reverse order of characters in string

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deblank Remove trailing whitespace from end of string or character array

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strtrim Remove leading and trailing whitespace from string array or character array

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strjust Justify string or character array

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strcmp Compare strings

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strcmpi Compare strings (case insensitive)

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strncmp Compare first n characters of strings (case sensitive)

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strncmpi Compare first n characters of strings (case insensitive)

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regexp Match regular expression (case sensitive)

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regexpi Match regular expression (case insensitive)

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regexprep Replace text using regular expression

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regexptranslate Translate text into regular expression

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Dates and Time

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datetime Arrays that represent points in time

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NaT Not-a-Time

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years Duration in years

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days Duration in days

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hours Duration in hours

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minutes Duration in minutes

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seconds Duration in seconds

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milliseconds Duration in milliseconds

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duration Lengths of time in fixed-length units

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calyears Calendar duration in years

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calquarters Calendar duration in quarters

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calmonths Calendar duration in months

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calweeks Calendar duration in weeks

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caldays Calendar duration in days

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caLendarduration Lengths of time in variable-length calendar units

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year Year number

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quarter Quarter number

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month Month number and name

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week Week number

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day Day number or name

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hour Hour number

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minute Minute number

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second Second number

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ymd Year, month, and day numbers of datetime

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hms Hour, minute, and second numbers of duration

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split Split calendar duration into numeric and duration units

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time Convert time of calendar duration to duration

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timeofday Elapsed time since midnight for datetimes

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isdatetime Determine if input is datetime array

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isduration Determine if input is duration array

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iscalendarduration Determine if input is calendar duration array

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isnat Determine NaT (Not-a-Time) elements

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isdst Determine daylight saving time elements

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isweekend Determine weekend elements

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timezones List time zones

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tzoffset Time zone offset from UTC

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between Calendar math differences

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caldiff Calendar math successive differences

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dateshift Shift date or generate sequence of dates and time

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isbetween Determine elements within date and time interval

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datenum Convert date and time to serial date number

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datevec Convert date and time to vector of components

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exceltime Convert MATLAB datetime to Excel date number

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juliandate Convert MATLAB datetime to Julian date

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posixtime Convert MATLAB datetime to POSIX time

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yyyymmdd Convert MATLAB datetime to YYYYMMDD numeric value

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addtodate Modify date number by field

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char Character array

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string String array

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datestr Convert date and time to string format

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now Current date and time as serial date number

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clock Current date and time as date vector

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date Current date string

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calendar Calendar for specified month

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eomday Last day of month

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weekday Day of week

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etime Time elapsed between date vectors

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Categorical Arrays

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categorical Array that contains values assigned to categories

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iscategorical Determine whether input is categorical array

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discretize Group data into bins or categories

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categories Categories of categorical array

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iscategory Test for categorical array categories

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isordinal Determine whether input is ordinal categorical array

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isprotected Determine whether categories of categorical array are protected

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addcats Add categories to categorical array

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mergecats Merge categories in categorical array

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removecats Remove categories from categorical array

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renamecats Rename categories in categorical array

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reordercats Reorder categories in categorical array

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setcats Set categories in categorical array

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summary Print summary of table, timetable, or categorical array

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countcats Count occurrences of categorical array elements by category

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isundefined Find undefined elements in categorical array

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Tables

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table Table array with named variables that can contain different types

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array2table Convert homogeneous array to table

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cell2table Convert cell array to table

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struct2table Convert structure array to table

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table2array Convert table to homogeneous array

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table2cell Convert table to cell array

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table2struct Convert table to structure array

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table2timetable Convert table to timetable

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timetable2table Convert timetable to table

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readtable Create table from file

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writetable Write table to file

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DetectImportoptions Create import options based on file content

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getvaropts Get variable import options

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setvaropts Set variable import options

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setvartype Set variable data types

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head Get top rows of table, timetable, or tall array

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tail Get bottom rows of table, timetable, or tall array

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summary Print summary of table, timetable, or categorical array

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height Number of table rows

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width Number of table variables

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istable Determine whether input is table

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sortrows Sort rows of matrix or table

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unique Unique values in array

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issortedrows Determine if matrix or table rows are sorted

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topkrows Top rows in sorted order

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addvars Add variables to table or timetable

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movevars Move variables in table or timetable

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removevars Delete variables from table or timetable

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splitvars Split multicolumn variables in table or timetable

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mergevars Combine table or timetable variables into multicolumn variable

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vartype Subscript into table or timetable by variable type

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rows2vars Reorient table or timetable so that rows become variables

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stack Stack data from multiple variables into single variable

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unstack Unstack data from single variable into multiple variables

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inner2outer Invert nested table-in-table hierarchy in tables or timetables

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join Combine two tables or timetables by rows using key variables

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innerjoin Inner join between two tables or timetables

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outerjoin Outer join between two tables or timetables

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union Set union of two arrays

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intersect Set intersection of two arrays

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ismember Array elements that are members of set array

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setdiff Set difference of two arrays

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setxor Set exclusive OR of two arrays

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ismissing Find missing values

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standArdizemissing Insert standard missing values

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rmmissing Remove missing entries

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fillmissing Fill missing values

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varfun Apply function to table or timetable variables

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rowfun Apply function to table or timetable rows

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findgroups Find groups and return group numbers

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splitapply Split data into groups and apply function

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groupsummary Group summary computations

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Timetables

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timetable Timetable array with time-stamped rows and variables of different types

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retime resample or aggregate data in timetable, and resolve duplicate or irregular times

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synchronize synchronize timetables to common time vector, and resample or aggregate data from input timetables

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lag Time-shift data in timetable

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table2timetable Convert table to timetable

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array2timetable Convert homogeneous array to timetable

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timetable2table Convert timetable to table

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istimetable Determine if input is timetable

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isregular Determine whether times in timetable are regular

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timerange Time range for timetable row subscripting

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withtol Time tolerance for timetable row subscripting

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vartype Subscript into table or timetable by variable type

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rmmissing Remove missing entries

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issorted Determine if array is sorted

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sortrows Sort rows of matrix or table

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unique Unique values in array

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Structures

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struct Structure array

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fieldnames Field names of structure, or public fields of COM or Java object

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getfield Field of structure array

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isfield Determine whether input is structure array field

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isstruct Determine whether input is structure array

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orderfields Order fields of structure array

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rmfield Remove fields from structure

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setfield Assign values to structure array field

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arrayfun Apply function to each element of array

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structfun Apply function to each field of scalar structure

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table2struct Convert table to structure array

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struct2table Convert structure array to table

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cell2struct Convert cell array to structure array

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struct2cell Convert structure to cell array

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Cell Arrays

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cell Cell array

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cell2mat Convert cell array to ordinary array of the underlying data type

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cell2struct Convert cell array to structure array

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cell2table Convert cell array to table

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celldisp Display cell array contents

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cellfun Apply function to each cell in cell array

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cellplot Graphically display structure of cell array

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cellstr Convert to cell array of character vectors

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iscell Determine whether input is cell array

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iscellstr Determine if input is cell array of character vectors

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mat2cell Convert array to cell array with potentially different sized cells

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num2cell Convert array to cell array with consistently sized cells

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strjoin Join text in array

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strsplit Split string at specified delimiter

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struct2cell Convert structure to cell array

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table2cell Convert table to cell array

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Function Handles

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feval Evaluate function

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func2str Construct character vector from function handle

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str2func Construct function handle from character vector

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localfunctions Function handles to all local functions in MATLAB file

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functions Information about function handle

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Map Containers

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containers.Map Object that maps values to unique keys

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isKey Determine if Map object contains key

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keys Return keys of Map object

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remove Delete key-value pairs from Map object

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values Return values of Map object

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Time Series

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Time Series Objects

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timeseries Create timeseries object
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addevent Add event to timeseries
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addsample Add data sample to timeseries object
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append Concatenate timeseries objects in time
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delevent Remove event from timeseries
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delsample Remove sample from timeseries object
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detrend Subtract mean or best-fit line from timeseries object
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filter Modify frequency content of timeseries objects
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idealfilter timeseries ideal filter
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plot Plot timeseries
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resample Resample timeseries time vector
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set Set timeseries properties
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setabstime Set timeseries times as date character vectors
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setinterpfunction Set default interpolation method for timeseries object
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setuniformtime Modify uniform timeseries time vector
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synchronize Synchronize and resample two timeseries objects using common time vector
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get Query timeseries properties
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getabstime Convert timeseries time vector to cell array
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getdatasamples Access timeseries data samples
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getdatasamplesize timeseries data sample size
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getinterpmethod timeseries interpolation method
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getqualitydesc timeseries data quality
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getsamples Subset of timeseries
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getsampleusingtime Subset of timeseries data
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gettsafteratevent Create timeseries at or after event
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gettsafterevent Create timeseries after event
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gettsatevent Create timeseries at event
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gettsbeforeatevent Create timeseries at or before event
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gettsbeforeevent Create timeseries before event
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gettsbetweenevents Create timeseries between events
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iqr Interquartile range of timeseries data
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max Maximum of timeseries data
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mean Mean of timeseries data
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median Median of timeseries data
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min Minimum of timeseries data
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std Standard deviation of timeseries data
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sum Sum of timeseries data
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var Variance of timeseries data
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Time Series Collections

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tscollection Create tscollection object
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addsampletocollection Add sample to tscollection
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addts Add timeseries to tscollection
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delsamplefromcollection Delete sample from tscollection
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horzcat Horizontally concatenate tscollection objects
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removets Remove timeseries from tscollection
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resample Resample tscollection time vector
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set Set tscollection properties
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setabstime Set tscollection times as date character vectors
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settimeseriesnames Rename timeseries in tscollection
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vertcat Vertically concatenate tscollection objects
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get Query tscollection properties
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getabstime Convert tscollection time vector to cell array
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getsampleusingtime Subset of tscollection data
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gettimeseriesnames Names of timeseries in tscollection
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isempty Determine if tscollection is empty
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length Length of tscollection time vector
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size Size of tscollection
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Time Series Events

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tsdata.event Create tsdata.event object
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findEvent Query tsdata.event by name
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get Query tsdata.event properties
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gEttimeStr Query tsdata.event times
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set Set tsdata.event properties
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Data Type Identification

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iscalendarduration Determine if input is calendar duration array

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iscategorical Determine whether input is categorical array

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iscell Determine whether input is cell array

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iscellstr Determine if input is cell array of character vectors

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ischar Determine if input is character array

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isdatetime Determine if input is datetime array

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isduration Determine if input is duration array

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isenum Determine if variable is enumeration

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isfloat Determine if input is floating-point array

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isgraphics True for valid graphics object handles

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isinteger Determine if input is integer array

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isjava Determine if input is Java object

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islogical Determine if input is logical array

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isnumeric Determine if input is numeric array

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isobject Determine if input is MATLAB object

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isreal Determine whether array is real

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isstring Determine if input is string array

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isstruct Determine whether input is structure array

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istable Determine whether input is table

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istimetable Determine if input is timetable

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is Detect state

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isa Determine if input is object of specified class

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class Determine class of object

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validateattributes Check validity of array

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whos List variables in workspace, with sizes and types

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Data Type Conversion

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char Character array

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cellstr Convert to cell array of character vectors

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int2str Convert integers to characters

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mat2str Convert matrix to characters

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num2str Convert numbers to character array

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str2double Convert string to double precision value

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str2num Convert character array to numeric array

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native2unicode Convert numeric bytes to Unicode character representation

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unicode2native Convert Unicode character representation to numeric bytes

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base2dec Convert text representing number in base N to decimal number

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bin2dec Convert text representation of binary number to decimal number

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dec2base Convert decimal number to character vector representing base N number

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dec2bin Convert decimal number to character vector representing binary number

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dec2hex Convert decimal number to character vector representing hexadecimal number

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hex2dec Convert text representation of hexadecimal number to decimal number

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hex2num Convert IEEE hexadecimal string to double-precision number

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num2hex Convert singles and doubles to IEEE hexadecimal strings

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table2array Convert table to homogeneous array

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table2cell Convert table to cell array

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table2struct Convert table to structure array

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array2table Convert homogeneous array to table

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cell2table Convert cell array to table

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struct2table Convert structure array to table

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cell2mat Convert cell array to ordinary array of the underlying data type

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cell2struct Convert cell array to structure array

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mat2cell Convert array to cell array with potentially different sized cells

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num2cell Convert array to cell array with consistently sized cells

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struct2cell Convert structure to cell array

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