splitapply doesn't split well into bins

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Amit Ifrach
Amit Ifrach on 11 Oct 2021
Commented: Matt J on 13 Oct 2021
לק"י
Hi guys,
I wanted splitapply command to split to 90 different bins. somewhy it returns only 50.
Here is the process I made:
First, 'cell1areas' (size - 18800X1) - a variable that contains vector of areas was loaded.
then 'bins' or 'groups' from 0 to 90000 in 1000 spacing was created in 'edges' variable.
after that, discretize function was applied to the area vector data. the max value of the variable dis is 62 (max(dis)).
valid function was apllied to check rather the data is a number or NaN.
last, splitapply function was called with @sum to sum all values for each group.
The problem is, that the spltsum variable have 50 'bins' or vector elements in it, instead of the desired 90 (which is the number of bins in edges) or even 62(!) like the discretize gave only 62 different numbers and not 90.
Thanks in advace, this community is great and really helpfull!
the code:
edges=[0 0:1000:90000 90000];
dis=discretize(cell1areas, edges);
valid=isfinite(cell1areas);
spltsum=splitapply(@sum , cell1areas(valid) , findgroups(dis(valid)) );

Accepted Answer

Matt J
Matt J on 11 Oct 2021
Edited: Matt J on 13 Oct 2021
You can use accumarray instead.
spltsum=accumarray(dis(valid), cell1areas(valid) , [90,1]);
  5 Comments
Matt J
Matt J on 13 Oct 2021
Not all 90 bins contain counts. If you don't tell accumarray how many bins you have, it will assume you only have max(dis(valid)) bins.

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