Extracting row of a matrix based on maximum value of a column element

Hello all:

I have a matrix as below. I want to build a new matrix based on maximum value at row 4 element. Here column 5 is the index matrix, column 1 is the year, column 2 is month and column 3 is date. I want to extract the row with maximum value in column 4. For example, the value with 2 in column 5 occurred twice. The respective values at column 4 are 50 and 100. I want to extract the row with value 100.

A=

1978  7  1  45  1
1978  7  11  50  2
1978  7  14  100  2
1978  7  23  120  3
1978  8  17  150  4
1978  8  23  130  5
1978  8  24  40  5
1978  8  25  200  5

Desired output B =

1978  7  1  45  1
1978  7  14  100  2
1978  7  23  120  3
1978  8  17  150  4
1978  8  25  200  5

[Poulomi Ganguli]

Hello, I solved the problem using ismember

unq_col = unique(Data_All(:,5));

          for jdx = 1:size(unq_col,1)
              matched = ismember(Data_All(:,5),unq_col(jdx,1),'rows');
              des_flow =  Data_All(matched,:);
              [Maxflow,ID] = max(des_flow(:,4));
              OUT(jdx,:) = des_flow(ID,:);
          end

Answer 1

[Stephen Cobeldick]

>> mat = [...
1978  7  1  45  1
1978  7  11  50  2
1978  7  14  100  2
1978  7  23  120  3
1978  8  17  150  4
1978  8  23  130  5
1978  8  24  40  5
1978  8  25  200  5]
>> tmp = sortrows(mat,[5,4]);
>> idx = [diff(tmp(:,5))>0;true];
>> out = tmp(idx,:)
out =
 1978      7      1     45      1
 1978      7     14    100      2
 1978      7     23    120      3
 1978      8     17    150      4
 1978      8     25    200      5