Get the filename of a loaded file

Hi,

I have a script that loads a file and do some data plotting. I am loading different files each time I run the script. I manually edit the file name since every time the name is different and comming from an unrelated system.

My script reads the file as follows:

load('\Data_record_file_20220714T121615.mat');

Question:

How can I register the file name in a variable? I want to later use the file name in a string (after trimming it) so that I can automatically include the file name on the plot title.

Thank you.

Fabián

Answer 1

[Star Strider]

Save the fille name as a string or character array first, then refer to it as any other variable —

filename = '\Data_record_file_20220714T121615.mat';

load(filename);

One option might be to store all the various file names in a cell array or string array, and then just subscript into it —

load_data = load(filecell{k});

where ‘k’ is the desired element of the cell array ‘filecell’ storing the file names.

It is always best to load into a structure output. This avoids problems such as overwriting existing variables, and other potential problems —

load_data = load(filename);

then refer to the fields of ‘load_data’ (or whatever you choose to call it) to recover the various variables.

.

[Fabian Grodek]

Thank you, Star! This seems to be what I need. Much appreciated!

[Fabian Grodek]

I will assign the filenames to a string array as they become available. Then, I will have this statement:

load_data = load(filecell{k});

Where I will only need to change the k index each time. Or even better. I can create a loop where I can generate a plot for each data file! On each loop I will have the filename available so that I can insert the proper title each time.

BTW, I tried this:

MyDataFile = load('\Data_record_file_20220714T121615.mat');

but then I couldn't find out how to retrieve the filename from the MyDataFile structure. I'm quite new to Matlab :-(

Many Thanks!

[Walter Roberson]

The file name is not returned when you load(). The only way to find it after the fact is to use dbstack() to locate the file name and line of code that you just executed, and then parse the matlab source for the routine that calls load() and read the quoted string from the source code.

If you have a red box of nails and a blue box of nails and you pull a nail out of one of the boxes, then you know that it is unlikely that the nail will have inscribed on it "This came from the blue box". MAT files are containers, and the loaded data does not get labeled with file name.

[Star Strider]

@Fabian Grodek — My pleasure!

@Walter Roberson — Thank you!

.

Answer 2

[桂生 李]

try

[FileName, FilePath] = uigetfile;

Answer 3

[Walter Roberson]

filename = '\Data_record_file_20220714T121615.mat';

load(filename);

[~, basename, ~] = fileparts(filename);
title( "Analysis of " + basename)

Note: we do not recommend that form of load(). We recommend that you assign the output of load() to a variable, which gives you a struct array with one field for each loaded variable; you would then pull fields out of the struct as needed. This is more robust and more efficient, and is needed if you later want to do code generation. There are situations in which MATLAB will ignore variables created by load() that does not have an output variable name.

[Fabian Grodek]

Walter, you mean you do not recommend the form:

load_data = load(filename); ?

[Walter Roberson]

load(filename); is not recommended. load_data = load(filename); is recommended instead.

[Fabian Grodek]

Understood. Thanks.