Hi I have m by n matrix,I want to find the index of the max. of each column.It can be found by [i j]:max(x,[],2).this gives the index of max of each column in vector i.I want if there is a repetion in vector i to be reset to 0.thanks

Hi I have m by n matrix,I want to find the index of the max. of each column.It can be found by [i j]:max(x,[],2).this gives the index of max of each column in vector i.I want if there is a repetion in vector i to be reset to 0.thanks

Answer 1

[Azzi Abdelmalek]

 m=[1 2 3;0 5 6;2 1 7;0 4 9]
[ii,jj]=max(m)

%[ii ji]=max(x,[],2) gives the max of each row

[yousef Yousef]

Yes,there is no repition,but if the matrix is big ,there will be repitions in vector jj. try:

r=randi(500,10,20);
[ii jj]=max(r)

 ii=483   486   467   476   398   480   480   465   459   468   398   499   481   456   427   473   479   411   391   465
jj=10     2     4     9     4     7     6     5     5     5     2     8     2     2     1     4     8     3     9     1

for example number 2 is repeated so manytimes

[Azzi Abdelmalek]

Ok, if 2 is repeated, what do you want to do?

[Azzi Abdelmalek]

Maybe you want

r=randi(500,10,20);
[ii jj]=max(r)
[kk,ee]=unique(jj,'stable') ;
idx=zeros(1,numel(jj));
idx(ee)=kk

[yousef Yousef]

Actually,you have done a big favor for me.I want to put zeros in case of repetitions. Thanks a lot I have just started with Matlab since 2 weeks and every time I stuck in some points. Thanks again

[yousef Yousef]

But when I use [ii jj]=max(r,[],2) instead of using [ii jj]=max(r).It does not work.Do you know why. I'm writing the max function in this way to find the max of each column.

[Azzi Abdelmalek]

No, you are looking for the max of each row, to find the maximum of each column

[ii ,jj]=max(r)

%or

[ii, jj]=max(r,[],1)