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writematrix

Write a matrix to a file

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Syntax

writematrix(A)
writematrix(A,filename)
writematrix(___,Name,Value)

Description

writematrix(A) writes homogeneous array A to a comma delimited text file. The file name is the workspace variable name of the array, appended with the extension .txt. If writematrix cannot construct the file name from the array name, then it writes to the file matrix.txt.

Each column of each variable in A becomes a column in the output file. The writematrix function overwrites any existing file.

example

writematrix(A,filename) writes to a file with the name and extension specified by filename.

writematrix determines the file format based on the specified extension. The extension must be one of the following:

  • .txt, .dat, or .csv for delimited text files

  • .xls, .xlsm, or .xlsx for Excel® spreadsheet files

  • .xlsb for Excel spreadsheet files supported on systems with Excel for Windows®

example

writematrix(___,Name,Value) writes an array to a file with additional options specified by one or more Name,Value pair arguments and can include any of the input arguments in previous syntaxes.

example

Examples

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Open Live Script

Create a matrix, write it to a comma-separated text file, and then write the matrix to another text file with a different delimiter character.

Create a matrix in the workspace. 

M = magic(5)
M = 5×5

    17    24     1     8    15
    23     5     7    14    16
     4     6    13    20    22
    10    12    19    21     3
    11    18    25     2     9

Write the matrix to a comma delimited text file and display the file contents. The writematrix function outputs a text file named M.txt.

writematrix(M)
type 'M.txt'
17,24,1,8,15
23,5,7,14,16
4,6,13,20,22
10,12,19,21,3
11,18,25,2,9

To write the same matrix to a text file with a different delimiter character, use the 'Delimiter' name-value pair.

writematrix(M,'M_tab.txt','Delimiter','tab')
type 'M_tab.txt'
17	24	1	8	15
23	5	7	14	16
4	6	13	20	22
10	12	19	21	3
11	18	25	2	9
Open Live Script

Create a matrix, write it to a spreadsheet file, and then read and display the contents of the file.

Create a matrix in the workspace. 

M = magic(5)
M = 5×5

    17    24     1     8    15
    23     5     7    14    16
     4     6    13    20    22
    10    12    19    21     3
    11    18    25     2     9

Write the matrix to a spreadsheet file.

writematrix(M,'M.xls')

Read and display the matrix from M.xls. 

readmatrix('M.xls')
ans = 5×5

    17    24     1     8    15
    23     5     7    14    16
     4     6    13    20    22
    10    12    19    21     3
    11    18    25     2     9
Open Live Script

Create a matrix and write it to a specified sheet and range in a spreadsheet file.

Create a matrix in the workspace. 

M = magic(5)
M = 5×5

    17    24     1     8    15
    23     5     7    14    16
     4     6    13    20    22
    10    12    19    21     3
    11    18    25     2     9

Write the matrix to M.xls, to the second worksheet in the file, starting at the third row.

writematrix(M,'M.xls','Sheet',2,'Range','A3:E8')

Read and display the matrix. 

readmatrix('M.xls','Sheet',2,'Range','A3:E8')
ans = 5×5

    17    24     1     8    15
    23     5     7    14    16
     4     6    13    20    22
    10    12    19    21     3
    11    18    25     2     9
Open Live Script

Append an array of data below existing data in a spreadsheet.

Create two matrices in the workspace.

M1 = magic(5)
M1 = 5×5

    17    24     1     8    15
    23     5     7    14    16
     4     6    13    20    22
    10    12    19    21     3
    11    18    25     2     9


M2 = [5 10 15 20 25; 30 35 40 45 50]
M2 = 2×5

     5    10    15    20    25
    30    35    40    45    50

Write the matrix M1 to a spreadsheet file, M.xls.

writematrix(M1,'M.xls')

Append the data in matrix M2 below the existing data in the spreadsheet file.

writematrix(M2,'M.xls','WriteMode','append')

Read the spreadsheet file and display the matrix. 

readmatrix('M.xls')
ans = 7×5

    17    24     1     8    15
    23     5     7    14    16
     4     6    13    20    22
    10    12    19    21     3
    11    18    25     2     9
     5    10    15    20    25
    30    35    40    45    50
Open Live Script

Append an array of data below existing data in a text file.

Create two matrices in the workspace.

fibonacci1 = [1 1 2 3; 5 8 13 21; 34 55 89 144]
fibonacci1 = 3×4

     1     1     2     3
     5     8    13    21
    34    55    89   144


fibonacci2 = [233 377 610 987]
fibonacci2 = 1×4

   233   377   610   987

Write the matrix fibonacci1 to a text file, fibonacci.txt.

writematrix(fibonacci1,'fibonacci.txt')

Append the data in fibonacci2 below the existing data in the text file.

writematrix(fibonacci2,'fibonacci.txt','WriteMode','append')

Read the text file and display the matrix. 

readmatrix('fibonacci.txt')
ans = 4×4

     1     1     2     3
     5     8    13    21
    34    55    89   144
   233   377   610   987

Input Arguments

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Input data, specified as a matrix.

File name, specified as a character vector or string scalar.

Depending on the location you are writing to, filename can take on one of these forms.

Location

Form

Current folder

To write to the current folder, specify the name of the file in filename.

Example: 'myTextFile.csv'

Other folders

To write to a folder different from the current folder, specify the full or relative path name in filename.

Example: 'C:\myFolder\myTextFile.csv'

Example: 'myFolder\myExcelFile.xlsx'

Remote Location

To write to a remote location, filename must contain the full path of the file specified as a uniform resource locator (URL) of the form:

scheme_name://path_to_file/my_file.ext

Based on the remote location, scheme_name can be one of the values in this table.

Remote Locationscheme_name
Amazon S3™s3
Windows Azure® Blob Storagewasb, wasbs
HDFS™hdfs

For more information, see Work with Remote Data.

Example: 's3://bucketname/path_to_file/my_file.xlsx'

  • If filename includes the file extension, then the writing function determines the file format from the extension. Otherwise, the writing function creates a comma separated text file and appends the extension .txt. Alternatively, you can specify filename without the file’s extension, and then include the 'FileType' name-value pair arguments to indicate the type of file.

  • If filename does not exist, then the writing function creates the file.

  • If filename is the name of an existing text file, then the writing function overwrites the file.

  • If filename is the name of an existing spreadsheet file, then the writing function writes the data to the specified location, but does not overwrite any values outside the range of the input data.

Data Types: char | string

Name-Value Arguments

Specify optional pairs of arguments as Name1=Value1,...,NameN=ValueN, where Name is the argument name and Value is the corresponding value. Name-value arguments must appear after other arguments, but the order of the pairs does not matter.

Before R2021a, use commas to separate each name and value, and enclose Name in quotes.

Example: 'FileType',text indicates that the variable names should not be included as the first row of the output file.

Text and Spreadsheet Files

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Type of file, specified as the comma-separated pair consisting of 'FileType' and a character vector or string containing 'text' or 'spreadsheet'.

The 'FileType' name-value pair must be used with the filename input argument. You do not need to specify the 'FileType' name-value pair argument if the filename input argument includes a standard file extension. The following standard file extensions are recognized by the writing function:

  • .txt, .dat, or .csv for delimited text files

  • .xls, .xlsm, or .xlsx for Excel spreadsheet files

  • .xlsb for Excel spreadsheet files supported on systems with Excel for Windows

Example: 'FileType','spreadsheet'

Data Types: char | string

Locale for writing dates, specified as the comma-separated pair consisting of 'DateLocale' and a character vector or a string scalar. When writing datetime values to the file, use DateLocale to specify the locale in which writematrix should write month and day-of-week names and abbreviations. The character vector or string takes the form xx_YY, where xx is a lowercase ISO 639-1 two-letter code indicating a language, and YY is an uppercase ISO 3166-1 alpha-2 code indicating a country. For a list of common values for the locale, see the Locale name-value pair argument for the datetime function.

The writing function ignores the 'DateLocale' parameter value whenever dates can be written as Excel-formatted dates.

Example: 'DateLocale','ja_JP'

Data Types: char | string

Writing mode, specified as the comma-separated pair consisting of 'WriteMode' and a character vector or a string scalar. Select a write mode based on the file type.

File Type

Write Mode

Text Files

  • 'overwrite' (default) — Overwrite the file.

  • 'append' — Append data to the file.

If the file you specified does not exist, then the writing function creates and writes data to a new file.

Spreadsheet Files

  • 'inplace' (default) — Update only the range occupied by the input data. The writing function does not alter any data outside of the range occupied by the input data.

    • If you do not specify a sheet, then the writing function writes to the first sheet.

  • 'overwritesheet' — Clear the specified sheet and write the input data to the cleared sheet.

    • If you do not specify a sheet, then the writing function clears the first sheet and writes the input data to it.

  • 'append' — The writing function appends the input data to the bottom of the occupied range of the specified sheet.

    • If you do not specify a sheet, then the writing function appends the input data to the bottom of the occupied range of the first sheet.

  • 'replacefile' — Remove all other sheets from the file, then clear and write the input data to the to the specified sheet.

    • If you do not specify a sheet, then the writing function removes all other sheets from the file, and then clears and writes the input data to the first sheet.

    • If the file you specified does not exist, then the writing function creates a new file and writes the input data to the first sheet.

  • When WriteVariableNames is set to true, the writing function does not support the write mode 'append'.

  • For spreadsheet files:

    • When the write mode is 'append', the writing function does not support the Range parameter.

    • If the file you specified does not exist, then the writing function performs the same actions as 'replacefile'.

Example: 'WriteMode','append'

Data Types: char | string

Text Files Only

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Field delimiter character, specified as the comma-separated pair consisting of 'Delimiter' and a character vector or string scalar containing one of these specifiers:

Specifier

Field Delimiter

','

'comma'

Comma. This is the default behavior.

' '

'space'

Space

'\t'

'tab'

Tab

';'

'semi'

Semicolon

'|'

'bar'

Vertical bar

You can use the 'Delimiter' name-value pair only for delimited text files.

Example: 'Delimiter','space'

Data Types: char | string

Indicator for writing quoted text, specified as "minimal", "all", or "none".

  • If QuoteStrings is "minimal", then the function encloses any variables containing the delimiter, line ending, or double-quote character in double-quote characters.

  • If QuoteStrings is "all", then the function encloses all text, categorical, datetime, and duration variables in double-quote characters.

  • If QuoteStrings is "none", then the function does not enclose variables in double-quote characters.

You can use the QuoteStrings name-value argument only with delimited text files.

Character encoding scheme associated with the file, specified as the comma-separated pair consisting of 'Encoding' and 'system' or a standard character encoding scheme name. When you do not specify any encoding, the writing function uses UTF-8 to write the file.

Example: 'Encoding','UTF-8' uses UTF-8 as the encoding.

Data Types: char | string

Spreadsheet Files Only

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Worksheet to write to, specified as the comma-separated pair consisting of 'Sheet' and a character vector or a string scalar containing the worksheet name or a positive integer indicating the worksheet index. The worksheet name cannot contain a colon (:). To determine the names of sheets in a spreadsheet file, use sheets = sheetnames(filename). For more information, see sheetnames.

Specify the worksheet to write to by name or index:

  • name — If the specified sheet name does not exist in the file, then the writing function adds a new sheet at the end of the worksheet collection.

  • index — If the specified sheet index is an index larger than the number of worksheets, then the writing function appends empty sheets until the number of worksheets in the workbook equals the sheet index. The writing function also generates a warning indicating that it has added a new worksheet.

You can use the 'Sheet' name-value pair only with spreadsheet files.

Example: 'Sheet',2

Example: 'Sheet', 'MySheetName'

Data Types: char | string | single | double | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64

Rectangular portion of worksheet to write to, specified as the comma-separated pair consisting of 'Range' and a character vector or string scalar in one of the following forms.

Form of the Value of Range Description
'Corner1'

Corner1 specifies the first cell of the region to write. The writing function writes the data starting at this cell.

Example: 'Range','D2'

'Corner1:Corner2'

Corner1 and Corner2 are two opposing corners that define the region to write. For example, 'D2:H4' represents the 3-by-5 rectangular region between the two corners D2 and H4 on the worksheet. The 'Range' name-value pair argument is not case sensitive, and uses Excel A1 reference style (see Excel help).

Example: 'Range','D2:H4'

  • If the range you specify is smaller than the size of the input data, then the writing function writes only a subset of the input data that fits into the range.

  • If the range you specify is larger than the size of the input data, then the writing function leaves the remainder of the region as it is.

The 'Range' name-value pair can only be used with Excel files.

Example: 'Range', 'A1:F10'

Data Types: char | string

Flag to start an instance of Microsoft Excel for Windows when writing spreadsheet data, specified as the comma-separated pair consisting of 'UseExcel' and either true, or false.

You can set the 'UseExcel' parameter to one of these values:

  • true — The writing function starts an instance of Microsoft Excel when writing the file.

  • false — The writing function does not start an instance of Microsoft Excel when writing the file. When operating in this mode, functionality for writing differs in the support of file formats and interactive features, such as formulas and macros.

UseExcel

true

false

Supported file formats

.xls, .xlsx, .xlsm, .xltx, .xltm, .xlsb, .ods

.xls, .xlsx, .xlsm, .xltx, .xltm

Support for interactive features, such as formulas and macros

Yes

No

When writing to spreadsheet files on Windows platforms, if you want to start an instance of Microsoft Excel, then set the 'UseExcel' parameter to true.

UseExcel is not supported in noninteractive, automated environments.

Automatically adjust column width, specified as true or false. If you specify a value of 0 or false, then writematrix will not automatically adjust the column widths to fit the data in the cells.

Example: 'AutoFitWidth',0

Preserve cell formatting of existing spreadsheet, specified as true or false. If you specify false, writematrix will not preserve the cell formatting of the spreadsheet. Formatting includes elements such as fonts, cell borders, and color-shaded cells.

When writing datetime data to a spreadsheet file, you must set both 'PreserveFormat' and the 'UseExcel' Name-Value pair to true to preserve the existing cell formatting. If 'UseExcel' is set to false and 'PreserveFormat' is set to true when writing datetime data to the file, writematrix will not preserve the existing cell formatting of the file.

Example: 'PreserveFormat',false

Limitations

writematrix does not support sparse matrices.

Algorithms

  • There are some instances where the writematrix function creates a file that does not represent the input data exactly. You will notice this when you use the readmatrix function to read that file. The resulting data might not have the exact same format or contents as the original array. If you need to save your array and retrieve it at a later time to match the original array exactly, with the same data and organization, then save it as a MAT-file. writematrix writes inexact data in the following instances:

    • writematrix writes out numeric data using long g format, and categorical or character data as unquoted text.

    • writematrix writes out arrays that have more than two dimensions as two dimensional arrays, with the trailing dimensions collapsed.

  • Excel converts Inf values to 65535. MATLAB® converts NaN, NaT, <undefined> categorical values, and <missing> string values to empty cells.

Version History

Introduced in R2019a

See Also

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