parse text file in matlab

To parse a text file in MATLAB, you can use the fscanf or textscan functions. Here is a simple example showing how to use textscan to read in comma-separated values (CSV) from a text file:

main.m
% Open the file for reading
fileID = fopen('myfile.txt', 'r');

% Define the format of the data in the file (e.g., '%f' for floating-point numbers)
formatSpec = '%f,%f,%f';

% Read in the data using textscan
C = textscan(fileID, formatSpec, 'Delimiter', ',', 'HeaderLines', 1);

% Close the file
fclose(fileID);

% Extract the data from the cell array
data = [C{1} C{2} C{3}];
377 chars
15 lines

In this example, myfile.txt is assumed to have headers on the first line and data in subsequent lines, with each value separated by commas. The formatSpec string specifies the data format (three floating-point numbers in this case), and the Delimiter option tells textscan to use commas as the separator between values.

Note that textscan returns the data as a cell array. To extract the data, you can convert it to a matrix or other data structure as needed.

You can also use regular expressions (regex) with textscan to handle more complex file formats. For example, to parse a file with both numeric and string data separated by arbitrary whitespace, you could use a format string like this:

main.m
formatSpec = '%s%f%s%f%s';
27 chars
2 lines

This would match a string, followed by a floating-point number, followed by another string, etc. To use this format string with textscan, you would need to specify a regular expression that matches the whitespace between values:

main.m
C = textscan(fileID, formatSpec, 'Delimiter', '', 'Whitespace', '\t\n\r ');
76 chars
2 lines

The Delimiter option is set to an empty string to indicate that there is no fixed delimiter between values (since there could be arbitrary whitespace). The Whitespace option specifies a regex pattern that matches tab, newline, carriage return, and space characters, which are the most common whitespace characters.