MATLAB Programming

12 Programming Tips
• Load spreadsheet, scientific, image, or audio data with appropriate
function.
• Load from a file using low-level file I/O functions (fread, fscanf, ...).
For more information: SeeLoadingaSavedWorkspaceandImporting
Data in the MATLAB Development Environment documentation, and “Using
Low-Level File I/O Functions” on page 6-103.
Viewing Variables in a MAT-File
To see what variables are saved in a MAT-file, use who or whos as shown
here (the .mat extension is not required). who returns a cell array and whos
returns a structure array.
mydataVariables = who('-file', 'mydata.mat');
Appending to a MAT-File
To save additional variables to an existing MAT-file, use
save matfilename -append
AnyvariablesyousavethatdonotyetexistintheMAT-fileareaddedto
the file. Any variables you save that already exist in the MAT-file overwrite
the old values.
Note Saving with the -append switch does not append additional elements to
an array that is already saved in a MAT-file. See the example below.
In this example, the second save operation does not concatenate new elements
to vector A, (makingA equal to [1 2 3 4 5 6 7 8]) in the MAT-file. Instead,
it replaces the 5 element vector, A, with a 3 element vector, also retaining all
other variables that were stored on the first save operation.
A = [1 2 3 4 5]; B = 12.5; C = rand(4);
save savefile;
A = [6 7 8];
save savefile A -append;
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