How to write a for loop to iterate through subjects IDs and their associated reaction times and create histogram
3 views (last 30 days)
Show older comments
I have a data set of several thousand values.
There are 10 unique subj_indx, 1 through 10. Each one represents an experimental subject. Each subject has a bunch of reaction times, rt.
I want to create a for loop that will go through this dataset and generate a histogram of the reaction time data for each subject.
I don't know where to start other than:
rt=subject_data.rt;
for id = 1:length(subj_idx)%loop for each unique id value
%rtIdx = 1:length(rt)
currentid = rt(rtIdx);
rtIdx = 0;
and I'm not sure even that's correct.
0 Comments
Accepted Answer
Paul
on 19 Sep 2022
Hi Rania,
Check out the splitapply function and workflow. Example with an array, but I think you can make it work with a table
x = [ones(100,1) rand(100,1);2*ones(100,1) rand(100,1)]; % example data
splitapply(@(x) histogram(axes(figure),x),x(:,2),findgroups(x(:,1)))
If you want to pretty-up the histograms, I think splitapply can be used with a user-defined function just as easily.
3 Comments
Paul
on 19 Sep 2022
Edited: Paul
on 19 Sep 2022
"I want to create a for loop that will go through this dataset and generate a histogram of the reaction time data for each subject."
That's exactly what the code in the Answer does. think of x(:,1) as the subj_idx and x(:,2) as the rt. A histogram was created for all of the rt data corresponding to subj_idx == 1 and a second histrogram for subj_idx == 2. Maybe this will clarify with a table as an example?
subj_idx = [ones(100,1);ones(100,1)*2];
rt = rand(200,1);
T = table(subj_idx,rt); % example table
splitapply(@(x) histogram(axes(figure),x),T.rt,findgroups(T.subj_idx))
Here's the same data with nicer plots
splitapply(@(rt,subj_idx) myfunc(rt,subj_idx),T.rt,T.subj_idx,findgroups(T.subj_idx))
function myfunc(rt,subj_idx)
figure;
histogram(rt)
title("RT histogram of subj_idx" + double(unique(subj_idx)));
xlabel('RT')
ylabel('Occurences')
end
More Answers (0)
See Also
Categories
Find more on Histograms in Help Center and File Exchange
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!