# Plot multiple histogram within 1 function

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Edited: Adam Danz on 15 Oct 2020
Hi all! I made some histograms, but now I'm trying to make a function that plots multiple histograms at the same time. I want 1 plot with 4 overlapping histograms of different colors and a legend. Can someone please explain to me how to do this? I tried to make a loop (see bottom) but it doesn't seem to work.
histogram_color = [0 .7 .7];
histogram(error1,'normalization','pdf','edgecolor',histogram_color,'facecolor',histogram_color,'facealpha',.5)
x = -90:1:90;
f1 = fitdist(error1,'kernel');
pdf1 = pdf(f1,x);
l1 = line(x,pdf1,'linestyle','-','color',histogram_color,'linewidth',3);
histogram_color = [0 0 .7];
histogram(error2,'normalization','pdf','edgecolor',histogram_color,'facecolor',histogram_color,'facealpha',.5)
x = -90:1:90;
f2 = fitdist(error2,'kernel');
pdf2 = pdf(f2,x);
l2 = line(x,pdf2,'linestyle','-','color',histogram_color,'linewidth',3);
x = -90:1:90;
for i = 1:length(out)
histogram(out(i),'normalization','pdf','edgecolor',histogram_color,'facecolor',histogram_color,'facealpha',.5);
f(i) = fitdist(out(i),'kernel');
pdf(i) = pdf(f(i),x);
l(i) = line(x,pdf(i),'linestyle','-','color',histogram_color,'linewidth',3);
end
Adam Danz on 14 Oct 2020
You're missing "hold on"
Otherwise the 2nd histogram replaces the first.

Sudhakar Shinde on 15 Oct 2020
[~,ErrorLength]= size(out);
for i =1:ErrorLength
hold on
histogram(out(:,i),'normalization','pdf')
hold off
end

Steven Lord on 14 Oct 2020
The "Plot Multiple Histograms" example on the documentation page shows how to superimpose two histogram plots using hold on.

res = S.res;
targets = res(:,7);
responses = res(:,8);
orx = [3,4,5,6];
tgt = [1,2,3,4];
num = numel(orx);
out = cell(1,num);
for k = 1:num
idx = targets==tgt(k);
resp = responses(idx);
ori = res(idx,orx(k));
err = resp - ori;
err(err<-90) = err(err<-90)+180;
err(err>90) = err(err>90)-180;
out{k} = err;
end
out = [out{:}];
ero1 = out(:,1);
ero2 = out(:,2);
ero3 = out(:,3);
ero4 = out(:,4);
Adam Danz on 15 Oct 2020
You only need to "hold on" once and that was mentioned in a comment under the question 13 hours prior to this sub-thread.
hold on % <--- Move here
[~,ErrorLength]= size(out);
for i =1:ErrorLength
% hold on <--- Remove
histogram(out(:,i),'normalization','pdf')
% hold off <--- remove or move out of the loop
end
Adam Danz on 15 Oct 2020
Edited: Adam Danz on 15 Oct 2020
"I did not work."
I doubt it. It's the same solution as Sudhakar Shinde's and you indicated that it worked. There must have been some other problem (which is likely given the new propblem follwing "clear all").
" I tried 'clear all' & now my whole thing is not working anymore"
'clear all' is rarely necessary. You likely were using a global variable named x and now it's no longer defined. If that's the case, it s a good lesson to never use global variables. Now you need to figure out where x was defined.