how to load a matfile and access & process its content.

I am explaining my doubt with an example.

Eg: suppose i load a matfile named 'validation.mat' using load command, the contents of it get stored under a variable named " validation" in my workspace. so now can retrieve its content using validation(1,1) ,and so on.(manually created matfile)

now i want to programmatically create a similar kind of matfile at particular directory and give it name "execution.mat". and i also want to load this newly created matfile using load command to workspace and perform actions like executiom(1,1) = 2; and so on.

also note that this nameword "execution" i am deriving from a field of structutre.

so psuedocode would go as:

1. file_name = struct.somefield ------> here filename contains "execution"
2. now using file_name which contains execution i want to create execution.mat,load execution and process it

Answer 1

[Sindar]

% create a structure with field 'somefield' containing the desired filename
mystruct = struct('somefield','execution')
% create some example data
myvar = rand(2,2);
% extract the filename mystruct
filename = mystruct.somefield;
% save a mat file named execution.mat containing myvar
save([filename '.mat'],'myvar')
% load data from execution.mat into the newstruct structure
newstruct = load([filename '.mat']);
% replace the row-1/column-1 data with 2
newstruct.myvar(1,1) = 2;
% overwrite execution.mat with the new value for myvar
% note that since myvar is a field of newstruct, you need the -struct argument to save it correctly
save([filename '.mat'],'-struct','newstruct')

Some notes:

• struct is an important function, don't overwrite it
• note that loading data from a matfile into a variable creates a structure with corresponding fields. I think this is generally a better idea than an unassigned load (e.g., load([filename '.mat']); ) which dumps the variables directly into the workspace
• If you want the names of variables themselves to be determined programmatically, read this and reconsider