Looping through data and finding maximum value in each bin

Question

Jaclyn 2013-8-21

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/85246-looping-through-data-and-finding-maximum-value-in-each-bin

I have a dataset:

ds = BIN VALUE ID
5     1 
6     2 
3     2 
7     1 
4     1

Bins are unique. I need to find the ID with the maximum VALUE for each BIN. Example output in the above example:

MAX = BIN VALUE ID 
      10  6     2  
      11  7     1

This was my attempt to loop through the data producing output where each column is a BIN and the row contain the VALUES. I was then going to find the maximum of each bin (column) but the values didn't sort right.

bin = unique(ds(:,1));
val = ds(:,2);
b=numel(bin);
a=cell(b,1);
for i=1:b
    a{i}=ds(ds(:,1)==idate(i),2:3); 
    for j=1:length(a{i})
        output(j,i)=(a{i}(j)); 
    end
end

I'm probably over complicating this. I have Matlab 2011. Thanks in advance for your time!

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Answer 1

Andrei Bobrov 2013-8-21

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https://ww2.mathworks.cn/matlabcentral/answers/85246-looping-through-data-and-finding-maximum-value-in-each-bin#answer_94729

在 MATLAB Online 中打开

ds = [...
     10  5     1
     10  6     2
     11  3     2
     11  7     1
     11  4     1 ];
d1 = sortrows(ds,[1 2]);
[~,ii] = unique(d1(:,1));
out = d1(ii,:);

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Jaclyn 2013-8-21

This worked perfectly, thank you!!

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Answer 2

David Sanchez 2013-8-21

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/85246-looping-through-data-and-finding-maximum-value-in-each-bin#answer_94726

在 MATLAB Online 中打开

You could try something like this:

ds = [     10  5     1 ;
     10  6     2 ;
     11  3     2 ;
     11  7     1 ;
     11  4     1 ];
sorted = sort(ds,1)
sorted =
      10     3     1
      10     4     1
      11     5     1
      11     6     2
      11     7     2
max_val = sorted(end,:)
max_val =
      11     7     2

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Answer 3

Azzi Abdelmalek 2013-8-21

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/85246-looping-through-data-and-finding-maximum-value-in-each-bin#answer_94727

编辑：Azzi Abdelmalek 2013-8-21

在 MATLAB Online 中打开

v=[10  5     1 
   10  6     2 
   11  3     2 
   11  7     1 
   11  4     1] 
[c1,ii,jj]=unique(v(:,1),'stable')
c2=accumarray(jj,v(:,2),[],@max)
m=[c1 c2]
out=v(all(ismember(v(:,1:2),m),2),:)
out=unique(out,'rows','stable')