Accumarray error: First input SUBS must contain positive integer subscripts.

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Hello,
The accumarray function is causing me problems - the error is embedded within the question. Attached you find a sample file and below you find the piece of code I wrote:
temp_raw_JE50=X0012_50(:,20)-X0012_50(:,17); % raw overall JE50
temp_AO50=ismember(X0012_50(:,13),0); % AO trials (0's) in col. 13 of temp_file_50
temp_raw_JE50AO= accumarray(temp_raw_JE50,temp_AO50); % raw JE50 for AO trials only
Could you please be so kind as to help me?
Bianca

Accepted Answer

Sean de Wolski
Sean de Wolski on 27 Jun 2016
[uval,~,subs] = unique(temp_raw_JE50);
accumarray(subs,vals)
You most likely want to accumulate by the unique values. Since these aren't necessarily positive integer indices, use unique first and pass the indices into accumarray.
  1 Comment
Bianca Elena Ivanof
Bianca Elena Ivanof on 28 Jun 2016
Edited: Bianca Elena Ivanof on 28 Jun 2016
Thank you - I've tried your option but the script keeps crashing (new error: 'Second input VAL must be a vector with one element for each row in SUBS, or a scalar.'), partly because I can't understand why you use [uval,~,subs] in the example above, so I may not be using it correctly - I know uval and subs refer to the values that come in brackets after accumarray, but I'm missing the big picture.
Is vals the same with uval?
Moreover, would accumarray(subs,vals) replace the accumarray(temp_raw_JE50,temp_AO50) in my script above or accumarray(subs,vals) comes before ismember and accumarray in my script?
Could you please be so kind as to explain?

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More Answers (1)

Andrei Bobrov
Andrei Bobrov on 28 Jun 2016
[uval,~,subs] = unique(X0012_50(:,20)-X0012_50(:,17));
temp_raw_JE50AO = accumarray(subs,~X0012_50(:,13));
out = [uval, temp_raw_JE50AO];
  4 Comments
Sean de Wolski
Sean de Wolski on 30 Jun 2016
Look at the documentation for examples and descriptions of what the pieces are:
doc unique

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