Matlab: Using Accumarray

Question

If I have a column of dates and a corresponding column of volume data, like this:

31,3
31,2
31,1
31,5
07,2
07,3
07,4
07,2
07,3
07,5
07,3
07,1
07,1
07,2
07,3
30,5
06,4

I want to add up the data in the right hand column, for each date. If I use accumarray like this:

orgSumVinDay=accumarray(dayIdx,vv); 
k=orgSumVinDay==0;
SumVininDay=orgSumVinDay;
SumVinDay(k)=[]

It works; I get:

which is correct because on the 31st, there were 3+2+1+5=11, etc.

However, I want to get a column showing the cumulative addition within each day, so that it looks like:

and I'm not sure how to achieve this. Thanks!

texnic · Accepted Answer · 2013-06-22 23:09:41Z

2

Cannot check it right now but I believe you should be able to do it with accumarray (..., [], @cumsum). The last parameter will replace the default function sum with cumsum.

answered Jun 22, 2013 at 23:09

texnic

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2 Comments

siegel Over a year ago

Strange, accumarray(dayStr,minuteVolumes, [],@cumsum) gives the error "The function 'cumsum' returned a non-scalar value." But if I use a different function, like @max for example, the results are correct.

siegel Over a year ago

This works! cell2mat(accumarray(dayStr,minuteVolumes,[],@(x){cumsum(x)})); Thanks!

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