MATLAB Answers

Anyway to determine if a variable exists in a mat file (in app designer environment)?

42 views (last 30 days)
Kris Hoffman
Kris Hoffman on 10 Jul 2018
Commented: Steven Lord on 10 Jul 2018
Pulling hair out trying to find a way to check for the existence of a variable in a 200+MB mat file. I obviously don't want to load into every function and I'm trying to stear clear of the assignin and evalin commands. So far I've tried..
[app.fileName,PathName] = uigetfile('*.mat','MultiSelect','off');
app.fileName = erase(app.fileName,".mat");
cd(PathName);
app.fileName;
m = matfile(app.fileName)
This gives me a 1x1 "matlab.io.MatFile" type in the workspace. And when I try to see if a certain variable exists using "exist" or "isfield", I get logical 0. I don't know if there is a way to convert the matfile contents into a list of some sort or if there's a simpler way to check for variables. I can pull the data out of the variable with no problem but when I simply ask if it exists..
if isfield(m,'SomeVariable')
SomeVariable = m.SomeVariable;
end
or
if exist('m.SomeVariable','var')
SomeVariable = m.SomeVariable;
end
  2 Comments
Steven Lord
Steven Lord on 10 Jul 2018
The census.mat file contains two variables, cdate and pop.
x = matfile('census.mat');
Does 'cdate' exist in census.mat?
varIsInMat = @(name) ~isempty(who(x, name));
checkcdate = varIsInMat('cdate')
Does 'doesnotexist' exist in census.mat? [I guess I gave that one away.]
checkDNE = varIsInMat('doesnotexist')

Sign in to comment.

Products


Release

R2018a

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!