Find Max value with index

Hello All, I have two vectors of size (100x1) named "groups" and "norms", groups vector contains labels such as

groups=[1 2 2 1 3 2 3]

and norms vector contains length of vectors that belongs to one of the groups.

norms=[0.4923 0.6023 0.5717 0.4296 0.5425 0.5101 0.5185]

Now I want to find the max value of norms in each group with their corresponding index position in norms vector. I have the following code which gets the max norm in each group but it does not return index.

maxs = accumarray(groups(:,1), norms(:,1), [], @max);

Any help will be appreciated. Thanks.

Answer 1

[Rik]

Your current code doesn't return a maximum value for each group. The code below should do what you need.

groups=[1 2 2 1 3 2 3];
norms=[0.4923 0.6023 0.5717 0.4296 0.5425 0.5101 0.5185];

grouplist=unique(groups);
num=numel(grouplist);
maxs=zeros(num,1);
maxs_idx=zeros(num,1);
for idx=1:num
    [maxs(idx),maxs_idx(idx)]=max(norms(groups==grouplist(idx)));
end

[iam]

Thanks for your response, but as I checked its not giving me the correct maximum values of each group.

[Stephen23]

@iam: please show us what the required output is. Testing code is very difficult if the required output is not known to us.