accumarray function for equal integer values

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Felix Flores James
Felix Flores James 2018-11-16
编辑： Felix Flores James 2018-11-16
Hey guys,
I have a question about the accumarray function.
I have a table containing columns B1 and B2. B1= [34.1; 34.2; 35.6; 35.7] and B2 shows corresponding intensities and is [600; 800; 200; 100] respectively. My first step is rounding the B1 values to a nominal value, resulting in B1 = [34; 34; 36; 36]. However, in the second step I would like to use the accumarray function for B1 and B2, but this only gives the accumulated B2 column, B2 = [1400; 300]. I would also like to see the B1 column in which duplicate nominal values are now single values. Thus, B1 = [34; 36].
accumarray.png
many thanks!

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采纳的回答

Bruno Luong
Bruno Luong 2018-11-16
B1 = [34.1; 34.2; 35.6; 35.7];
B2 = [600; 800; 200; 100];
Br1 = round(B1);
u = unique(Br1);
[~,J] = ismember(Br1, u);
B2s = accumarray(J(:),B2);
s = [u B2s];
s(J,:)
  1 个评论
Stephen23
Stephen23 2018-11-16
Felix Flores James's "Answer" moved here and formatted properly:
Bruno,
Thank you for your answer. You're completely right, I should post data/code so that you guys can easily copy and past it in MATLAB. I will do that from now on.
It worked! Thank you!
>> B1 = [34.1; 34.2; 35.6; 35.7];
B2 = [600; 800; 200; 100];
Br1 = round(B1);
u = unique(Br1);
[~,J] = ismember(Br1, u);
B2s = accumarray(J(:),B2);
s = [u B2s];
s(J,:);
>> C = [u B2s]
C =
34 1400
36 300

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更多回答（1 个）

Andrei Bobrov
Andrei Bobrov 2018-11-16
编辑：Andrei Bobrov 2018-11-16
B1 = [34.1; 34.2; 35.6; 35.7];
B2 = [600; 800; 200; 100];
B = table(B1,B2);
B.B1 = round(B.B1);
Bnew = varfun(@sum,B,'GroupingVariables','B1');

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