# Elementwise diff() with an condition

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Philipp on 13 Mar 2013
I have an array of cells which contains numeric arrays of different lengths, lets call that array X. I want to write a function that writes the diff(cell2mat(X(i))) to and array of cells Y(i). The problem is when I want to add a condition i.e. only write the diff of two elements in the result vector when the difference is <= B. Below my code:
function[Y] = diffleq2(X)
len = length(X);
for i = 1:len
Y(i) = {diff(cell2mat(X(i)))};
end
X is of the form of
X = {[1,2,4,5],[23,12,13]};
just with a lot more cells. Obviously the new function would look like this
function[Y] = diffleq2(X,B)

ChristianW on 13 Mar 2013
X = {[1,2,4,5],[23,12,13]};
Y = cellfun(@diff,X,'un',0);
B = 1.5;
Ycut = cellfun(@(x) x(abs(x)>B),Y,'un',0);
Philipp on 13 Mar 2013
Edited: Philipp on 13 Mar 2013
Thanks for the answer. The first part works nicely (I didn't know about the cellfun function) - this is great.
But I still have problem with the last line where I want to remove all entries > B. Ycut is just the same as Y. Can you explain me the syntax of the function you passed as argument?
Edit: Figured it out - thanks again :)

Azzi Abdelmalek on 13 Mar 2013
Edited: Azzi Abdelmalek on 13 Mar 2013
X = {[1,2,4,5],[23,12,13]}
B=1
for k=1:numel(X)
b=diff(X{k})
b(b>B)=[]
out{k}=b
end

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