MATLAB Function Reference

textread - Read data from text file; write to multiple outputs

Note   The textscan function is intended as a replacement for both textread and strread.

Graphical Interface

As an alternative to textread, use the Import Wizard. To activate the Import Wizard, select Import Data from the File menu.

Syntax

[A,B,C,...] = textread('filename','format')
[A,B,C,...] = textread('filename','format',N)
[...] = textread(...,'param','value',...)

Description

[A,B,C,...] = textread('filename','format') reads data from the file 'filename' into the variables A,B,C, and so on, using the specified format, until the entire file is read. The filename and format inputs are strings, each enclosed in single quotes. textread is useful for reading text files with a known format. textread handles both fixed and free format files.

Note   When reading large text files, reading from a specific point in a file, or reading file data into a cell array rather than multiple outputs, you might prefer to use the textscan function.

textread matches and converts groups of characters from the input. Each input field is defined as a string of non-white-space characters that extends to the next white-space or delimiter character, or to the maximum field width. Repeated delimiter characters are significant, while repeated white-space characters are treated as one.

The format string determines the number and types of return arguments. The number of return arguments is the number of items in the format string. The format string supports a subset of the conversion specifiers and conventions of the C language fscanf routine. Values for the format string are listed in the table below. White-space characters in the format string are ignored.

[A,B,C,...] = textread('filename','format',N) reads the data, reusing the format string N times, where N is an integer greater than zero. If N is smaller than zero, textread reads the entire file.

[...] = textread(...,'param','value',...) customizes textread using param/value pairs, as listed in the table below.

Note   When textread reads a consecutive series of whitespace values, it treats them as one white space. When it reads a consecutive series of delimiter values, it treats each as a separate delimiter.

Remarks

If you want to preserve leading and trailing spaces in a string, use the whitespace parameter as shown here:

textread('myfile.txt', '%s', 'whitespace', '')
ans = 
    '   An  example      of preserving    spaces      '

Examples

Example 1 — Read All Fields in Free Format File Using %

The first line of mydata.dat is

Sally    Level1 12.34 45 Yes

Read the first line of the file as a free format file using the % format.

[names, types, x, y, answer] = textread('mydata.dat', ...
'%s %s %f %d %s', 1)

returns

names = 
    'Sally'
types = 
    'Level1'
x =
  12.34000000000000
y =
    45
answer = 
    'Yes'

Example 2 — Read as Fixed Format File, Ignoring the Floating Point Value

The first line of mydata.dat is

Sally    Level1 12.34 45 Yes

Read the first line of the file as a fixed format file, ignoring the floating-point value.

[names, types, y, answer] = textread('mydata.dat', ...
'%9c %5s %*f %2d %3s', 1)

returns

names =
Sally    
types = 
    'Level1'
y =
    45
answer = 
    'Yes'

%*f in the format string causes textread to ignore the floating point value, in this case, 12.34.

Example 3 — Read Using Literal to Ignore Matching Characters

The first line of mydata.dat is

Sally    Type1 12.34 45 Yes

Read the first line of the file, ignoring the characters Type in the second field.

[names, typenum, x, y, answer] = textread('mydata.dat', ...
'%s Type%d %f %d %s', 1)

returns

names = 
    'Sally'
typenum =
    1
x =
  12.34000000000000
y =
    45
answer = 
    'Yes'

Type%d in the format string causes the characters Type in the second field to be ignored, while the rest of the second field is read as a signed integer, in this case, 1.

Example 4 — Specify Value to Fill Empty Cells

For files with empty cells, use the emptyvalue parameter. Suppose the file data.csv contains:

1,2,3,4,,6
7,8,9,,11,12

Read the file using NaN to fill any empty cells:

data = textread('data.csv', '', 'delimiter', ',', ... 
                'emptyvalue', NaN);

Example 5 — Read M-File into a Cell Array of Strings

Read the file fft.m into cell array of strings.

file = textread('fft.m', '%s', 'delimiter', '\n', ...
                'whitespace', '');

See Also

textscan, dlmread, csvread, strread, fscanf

Text Properties

textscan