Julia for MATLAB Users/Core Language/Language Fundamentals

Language Fundamentals 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. __TOC__ Entering Commands Related: Julia REPL ans Most recent answer Julia's ans is functionally basically identical, though note that it is available only at the REPL. clc Clear Command Window 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 There doesn't appear to be an equivalent Julia REPL command. format Set Command Window output display format There is no drop-in equivalent in the Julia REPL or IJulia for globally setting the output format. home Send cursor home Ctrl L is functionally equivalent in the Julia REPL. iskeyword Determine whether input is MATLAB keyword There doesn't appear to be an equivalent Julia command, but see Keywords in the Julia manual. more Control paged output for Command Window Matrices and Arrays See Multi-dimensional Arrays in the Julia Manual. zeros Create array of all zeros; ones Create array of all ones 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 See Julia's rand. true Logical 1 (true); false Logical 0 (false) eye Identity matrix 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 blkdiag Construct block diagonal matrix from input arguments cat Concatenate arrays along specified dimension horzcat Concatenate arrays horizontally See Julia's hcat function vertcat Concatenate arrays vertically repelem Repeat copies of array elements repmat Repeat copies of array linspace Generate linearly spaced vector logspace Generate logarithmically spaced vector freqspace Frequency spacing for frequency response meshgrid 2-D and 3-D grids ndgrid Rectangular grid in N-D space length Length of largest array dimension 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 ndims Number of array dimensions In Julia, ndims is similar but not identical. For instance, Julia does not ignore singleton dimensions. numel Number of array elements In Julia, length is equivalent. isscalar Determine whether input is scalar isvector Determine whether input is vector ismatrix Determine whether input is matrix isrow Determine whether input is row vector iscolumn Determine whether input is column vector isempty Determine whether array is empty sort Sort array elements sortrows Sort rows of matrix or table issorted Determine if array is sorted issortedrows Determine if matrix or table rows are sorted topkrows Top rows in sorted order flip Flip order of elements fliplr Flip array left to right flipud Flip array up to down rot90 Rotate array 90 degrees transpose Transpose vector or matrix ctranspose Complex conjugate transpose permute Rearrange dimensions of N-D array ipermute Inverse permute dimensions of N-D array circshift Shift array circularly shiftdim Shift dimensions reshape Reshape array squeeze Remove singleton dimensions 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 end Terminate block of code, or indicate last array index Julia's end is basically equivalent. ind2sub Subscripts from linear index sub2ind Convert subscripts to linear indices Operators and Elementary Operations See Mathematical Operations and Elementary Functions in the Julia manual. Arithmetic plus Addition uplus Unary plus minus Subtraction uminus Unary minus times Element-wise multiplication rdivide Right array division ldivide Left array division power Element-wise power mtimes Matrix Multiplication mrdivide Solve systems of linear equations xA = B for x mldivide Solve systems of linear equations Ax = B for x mpower Matrix power cumprod Cumulative product cumsum Cumulative sum diff Differences and Approximate Derivatives movsum Moving sum prod Product of array elements sum Sum of array elements ceil Round toward positive infinity fix Round toward zero floor Round toward negative infinity idivide Integer division with rounding option mod Remainder after division (modulo operation) rem Remainder after division round Round to nearest decimal or integer bsxfun Apply element-wise operation to two arrays with implicit expansion enabled Relational Operations eq Determine equality ge Determine greater than or equal to gt Determine greater than le Determine less than or equal to lt Determine less than ne Determine inequality isequal Determine array equality isequaln Determine array equality, treating NaN values as equal Logical Operations Logical Operators: Short-circuit Logical operations with short-circuiting and Find logical AND not Find logical NOT or Find logical OR xor Find logical exclusive-OR all Determine if all array elements are nonzero or true any Determine if any array elements are nonzero false Logical 0 (false) find Find indices and values of nonzero elements In Julia, findall provides similar functionality. See also findfirst, findlast, findnext and findprev. islogical Determine if input is logical array logical Convert numeric values to logicals true Logical 1 (true) Set Operations intersect Set intersection of two arrays ismember Array elements that are members of set array ismembertol Members of set within tolerance issorted Determine if array is sorted setdiff Set difference of two arrays setxor Set exclusive OR of two arrays union Set union of two arrays unique Unique values in array uniquetol Unique values within tolerance join Combine two tables or timetables by rows using key variables innerjoin Inner join between two tables or timetables outerjoin Outer join between two tables or timetables Bit-Wise Operations bitand Bit-wise AND bitcmp Bit-wise complement bitget Get bit at specified position bitor Bit-wise OR bitset Set bit at specific location bitshift Shift bits specified number of places bitxor Bit-wise XOR swapbytes Swap byte ordering Data Types See Types in the Julia manual. Numeric Types double Double-precision arrays single Single-precision arrays int8 8-bit signed integer arrays int16 16-bit signed integer arrays int32 32-bit signed integer arrays int64 64-bit signed integer arrays uint8 8-bit unsigned integer arrays uint16 16-bit unsigned integer arrays uint32 32-bit unsigned integer arrays uint64 64-bit unsigned integer arrays cast Cast variable to different data type typecast Convert data types without changing underlying data isinteger Determine if input is integer array isfloat Determine if input is floating-point array isnumeric Determine if input is numeric array isreal Determine whether array is real isfinite Array elements that are finite isinf Array elements that are infinite isnan Array elements that are NaN eps Floating-point relative accuracy flintmax Largest consecutive integer in floating-point format Inf Infinity intmax Largest value of specified integer type intmin Smallest value of specified integer type NaN Not-a-Number realmax Largest positive floating-point number realmin Smallest positive normalized floating-point number Characters and Strings string String array strings Create array of strings with no characters join Combine strings char Character array cellstr Convert to cell array of character vectors blanks Create character array of blanks newline Create newline character compose Convert data into formatted string array sprintf Format data into string strcat Concatenate strings horizontally cOnverTcHarstostrings Convert character arrays to string arrays, leaving other arrays unaltered cOnvertsTrIngstoChars Convert string arrays to character arrays, leaving other arrays unaltered ischar Determine if input is character array iscellstr Determine if input is cell array of character vectors isstring Determine if input is string array isStringScalar Determine if input is string array with one element strlength Length of strings in string array isstrprop Determine if string is of specified category isletter Determine which characters are letters isspace Determine which characters are space characters contains Determine if pattern is in string count Count occurrences of pattern in string endsWith Determine if string ends with pattern StartsWith Determine if string starts with pattern strfind Find one string within another sscanf Read formatted data from string replace Find and replace substrings in string array rEplacebetween Replace substrings identified by indicators that mark their starts and ends strrep Find and replace substring join Combine strings split Split strings in string array splitlines Split string at newline characters strjoin Join text in array strsplit Split string at specified delimiter strtok Selected parts of string erase Delete substrings within strings erasebetween Delete substrings between indicators that mark starts and ends of substrings eXtractAfter Extract substring after specified position eXtractBefore Extract substring before specified position eXtractbetween Extract substrings between indicators that mark starts and ends of substrings InsertAfter Insert string after specified substring InsertBefore Insert string before specified substring pad Add leading or trailing characters to strings strip Remove leading and trailing characters from string lower Convert string to lowercase upper Convert string to uppercase reverse Reverse order of characters in string deblank Remove trailing whitespace from end of string or character array strtrim Remove leading and trailing whitespace from string array or character array strjust Justify string or character array strcmp Compare strings strcmpi Compare strings (case insensitive) strncmp Compare first n characters of strings (case sensitive) strncmpi Compare first n characters of strings (case insensitive) regexp Match regular expression (case sensitive) regexpi Match regular expression (case insensitive) regexprep Replace text using regular expression regexptranslate Translate text into regular expression Dates and Time datetime Arrays that represent points in time NaT Not-a-Time years Duration in years days Duration in days hours Duration in hours minutes Duration in minutes seconds Duration in seconds milliseconds Duration in milliseconds duration Lengths of time in fixed-length units calyears Calendar duration in years calquarters Calendar duration in quarters calmonths Calendar duration in months calweeks Calendar duration in weeks caldays Calendar duration in days caLendarduration Lengths of time in variable-length calendar units year Year number quarter Quarter number month Month number and name week Week number day Day number or name hour Hour number minute Minute number second Second number ymd Year, month, and day numbers of datetime hms Hour, minute, and second numbers of duration split Split calendar duration into numeric and duration units time Convert time of calendar duration to duration timeofday Elapsed time since midnight for datetimes isdatetime Determine if input is datetime array isduration Determine if input is duration array iscalendarduration Determine if input is calendar duration array isnat Determine NaT (Not-a-Time) elements isdst Determine daylight saving time elements isweekend Determine weekend elements timezones List time zones tzoffset Time zone offset from UTC between Calendar math differences caldiff Calendar math successive differences dateshift Shift date or generate sequence of dates and time isbetween Determine elements within date and time interval datenum Convert date and time to serial date number datevec Convert date and time to vector of components exceltime Convert MATLAB datetime to Excel date number juliandate Convert MATLAB datetime to Julian date posixtime Convert MATLAB datetime to POSIX time yyyymmdd Convert MATLAB datetime to YYYYMMDD numeric value addtodate Modify date number by field char Character array string String array datestr Convert date and time to string format now Current date and time as serial date number clock Current date and time as date vector date Current date string calendar Calendar for specified month eomday Last day of month weekday Day of week etime Time elapsed between date vectors Categorical Arrays categorical Array that contains values assigned to categories iscategorical Determine whether input is categorical array discretize Group data into bins or categories categories Categories of categorical array iscategory Test for categorical array categories isordinal Determine whether input is ordinal categorical array isprotected Determine whether categories of categorical array are protected addcats Add categories to categorical array mergecats Merge categories in categorical array removecats Remove categories from categorical array renamecats Rename categories in categorical array reordercats Reorder categories in categorical array setcats Set categories in categorical array summary Print summary of table, timetable, or categorical array countcats Count occurrences of categorical array elements by category isundefined Find undefined elements in categorical array Tables table Table array with named variables that can contain different types array2table Convert homogeneous array to table cell2table Convert cell array to table struct2table Convert structure array to table table2array Convert table to homogeneous array table2cell Convert table to cell array table2struct Convert table to structure array table2timetable Convert table to timetable timetable2table Convert timetable to table readtable Create table from file writetable Write table to file DetectImportoptions Create import options based on file content getvaropts Get variable import options setvaropts Set variable import options setvartype Set variable data types head Get top rows of table, timetable, or tall array tail Get bottom rows of table, timetable, or tall array summary Print summary of table, timetable, or categorical array height Number of table rows width Number of table variables istable Determine whether input is table sortrows Sort rows of matrix or table unique Unique values in array issortedrows Determine if matrix or table rows are sorted topkrows Top rows in sorted order addvars Add variables to table or timetable movevars Move variables in table or timetable removevars Delete variables from table or timetable splitvars Split multicolumn variables in table or timetable mergevars Combine table or timetable variables into multicolumn variable vartype Subscript into table or timetable by variable type rows2vars Reorient table or timetable so that rows become variables stack Stack data from multiple variables into single variable unstack Unstack data from single variable into multiple variables inner2outer Invert nested table-in-table hierarchy in tables or timetables join Combine two tables or timetables by rows using key variables innerjoin Inner join between two tables or timetables outerjoin Outer join between two tables or timetables union Set union of two arrays intersect Set intersection of two arrays ismember Array elements that are members of set array setdiff Set difference of two arrays setxor Set exclusive OR of two arrays ismissing Find missing values standArdizemissing Insert standard missing values rmmissing Remove missing entries fillmissing Fill missing values varfun Apply function to table or timetable variables rowfun Apply function to table or timetable rows findgroups Find groups and return group numbers splitapply Split data into groups and apply function groupsummary Group summary computations Timetables timetable Timetable array with time-stamped rows and variables of different types retime resample or aggregate data in timetable, and resolve duplicate or irregular times synchronize synchronize timetables to common time vector, and resample or aggregate data from input timetables lag Time-shift data in timetable table2timetable Convert table to timetable array2timetable Convert homogeneous array to timetable timetable2table Convert timetable to table istimetable Determine if input is timetable isregular Determine whether times in timetable are regular timerange Time range for timetable row subscripting withtol Time tolerance for timetable row subscripting vartype Subscript into table or timetable by variable type rmmissing Remove missing entries issorted Determine if array is sorted sortrows Sort rows of matrix or table unique Unique values in array Structures struct Structure array fieldnames Field names of structure, or public fields of COM or Java object getfield Field of structure array isfield Determine whether input is structure array field isstruct Determine whether input is structure array orderfields Order fields of structure array rmfield Remove fields from structure setfield Assign values to structure array field arrayfun Apply function to each element of array structfun Apply function to each field of scalar structure table2struct Convert table to structure array struct2table Convert structure array to table cell2struct Convert cell array to structure array struct2cell Convert structure to cell array Cell Arrays cell Cell array cell2mat Convert cell array to ordinary array of the underlying data type cell2struct Convert cell array to structure array cell2table Convert cell array to table celldisp Display cell array contents cellfun Apply function to each cell in cell array cellplot Graphically display structure of cell array cellstr Convert to cell array of character vectors iscell Determine whether input is cell array iscellstr Determine if input is cell array of character vectors mat2cell Convert array to cell array with potentially different sized cells num2cell Convert array to cell array with consistently sized cells strjoin Join text in array strsplit Split string at specified delimiter struct2cell Convert structure to cell array table2cell Convert table to cell array Function Handles feval Evaluate function func2str Construct character vector from function handle str2func Construct function handle from character vector localfunctions Function handles to all local functions in MATLAB file functions Information about function handle Map Containers containers.Map Object that maps values to unique keys isKey Determine if Map object contains key keys Return keys of Map object remove Delete key-value pairs from Map object values Return values of Map object Time Series Time Series Objects timeseries Create timeseries object addevent Add event to timeseries addsample Add data sample to timeseries object append Concatenate timeseries objects in time delevent Remove event from timeseries delsample Remove sample from timeseries object detrend Subtract mean or best-fit line from timeseries object filter Modify frequency content of timeseries objects idealfilter timeseries ideal filter plot Plot timeseries resample Resample timeseries time vector set Set timeseries properties setabstime Set timeseries times as date character vectors setinterpfunction Set default interpolation method for timeseries object setuniformtime Modify uniform timeseries time vector synchronize Synchronize and resample two timeseries objects using common time vector get Query timeseries properties getabstime Convert timeseries time vector to cell array getdatasamples Access timeseries data samples getdatasamplesize timeseries data sample size getinterpmethod timeseries interpolation method getqualitydesc timeseries data quality getsamples Subset of timeseries getsampleusingtime Subset of timeseries data gettsafteratevent Create timeseries at or after event gettsafterevent Create timeseries after event gettsatevent Create timeseries at event gettsbeforeatevent Create timeseries at or before event gettsbeforeevent Create timeseries before event gettsbetweenevents Create timeseries between events iqr Interquartile range of timeseries data max Maximum of timeseries data mean Mean of timeseries data median Median of timeseries data min Minimum of timeseries data std Standard deviation of timeseries data sum Sum of timeseries data var Variance of timeseries data Time Series Collections tscollection Create tscollection object addsampletocollection Add sample to tscollection addts Add timeseries to tscollection delsamplefromcollection Delete sample from tscollection horzcat Horizontally concatenate tscollection objects removets Remove timeseries from tscollection resample Resample tscollection time vector set Set tscollection properties setabstime Set tscollection times as date character vectors settimeseriesnames Rename timeseries in tscollection vertcat Vertically concatenate tscollection objects get Query tscollection properties getabstime Convert tscollection time vector to cell array getsampleusingtime Subset of tscollection data gettimeseriesnames Names of timeseries in tscollection isempty Determine if tscollection is empty length Length of tscollection time vector size Size of tscollection Time Series Events tsdata.event Create tsdata.event object findEvent Query tsdata.event by name get Query tsdata.event properties gEttimeStr Query tsdata.event times set Set tsdata.event properties Data Type Identification iscalendarduration Determine if input is calendar duration array iscategorical Determine whether input is categorical array iscell Determine whether input is cell array iscellstr Determine if input is cell array of character vectors ischar Determine if input is character array isdatetime Determine if input is datetime array isduration Determine if input is duration array isenum Determine if variable is enumeration isfloat Determine if input is floating-point array isgraphics True for valid graphics object handles isinteger Determine if input is integer array isjava Determine if input is Java object islogical Determine if input is logical array isnumeric Determine if input is numeric array isobject Determine if input is MATLAB object isreal Determine whether array is real isstring Determine if input is string array isstruct Determine whether input is structure array istable Determine whether input is table istimetable Determine if input is timetable is Detect state isa Determine if input is object of specified class class Determine class of object validateattributes Check validity of array whos List variables in workspace, with sizes and types Data Type Conversion char Character array cellstr Convert to cell array of character vectors int2str Convert integers to characters mat2str Convert matrix to characters num2str Convert numbers to character array str2double Convert string to double precision value str2num Convert character array to numeric array native2unicode Convert numeric bytes to Unicode character representation unicode2native Convert Unicode character representation to numeric bytes base2dec Convert text representing number in base N to decimal number bin2dec Convert text representation of binary number to decimal number dec2base Convert decimal number to character vector representing base N number dec2bin Convert decimal number to character vector representing binary number dec2hex Convert decimal number to character vector representing hexadecimal number hex2dec Convert text representation of hexadecimal number to decimal number hex2num Convert IEEE hexadecimal string to double-precision number num2hex Convert singles and doubles to IEEE hexadecimal strings table2array Convert table to homogeneous array table2cell Convert table to cell array table2struct Convert table to structure array array2table Convert homogeneous array to table cell2table Convert cell array to table struct2table Convert structure array to table cell2mat Convert cell array to ordinary array of the underlying data type cell2struct Convert cell array to structure array mat2cell Convert array to cell array with potentially different sized cells num2cell Convert array to cell array with consistently sized cells struct2cell Convert structure to cell array