how to find the max element in each column and row and replace it with 1. If conflicting elements occur, look for the next max element.

hallo, i have this code and this code select the high value element but it just select the element with different column. help me finish the code so the element can be selected with different columns and rows. thankss

U=3;
D=3;
MX= zeros(U,D);
MB= zeros(U,D);
MP=rand(3)
for y=1:U
    x=max(max(MP))
    [U,D] = find(MP==x)
    MP(U,:)=0
    MX(U,D)=MP(U,D)
    MB(U,D)=1
end

[the cyclist]

It is not clear to me what you want your code to do. Can you give an example or two of input and desired output from your code?

For example, if the input were

MP = [8 1 6;
      3 5 7;
      4 9 2]

what should the output be?

[Raja Zufar]

i try used different matrix because that have done different matrix result row and column if running the code, output would be like this:

MP = [8 9 1;
      3 5 7; 
      4 6 2]
  
MPouput =   [0 1 0;
             0 0 1; 
             1 0 0]

[Ameer Hamza]

Can you explain how MPouput is created from MP?

[Raja Zufar]

first, MP selected the max value of the matrix i assume [9 P(1,2)] and change it to '1'

second, MP finds the max value but cannot be the same as row and column P (2,1) and MP select [7 P(2,3) and change it to '1'

third, MP find the max valu but cannot be the same as row and column P(2,1) and P(2,3) and MP select [4 P(3,1) and change it to '1'

Answer 1

[Rajil Kansal]

Hey,

I am assuming that you want to find max element in each column and row and replace them with 1. Also only a single 1 should be present in each row and column in final output, If conflicting element occurs look for next max element.

This could be achieved by this code:

MP = [8 9 1;3 5 7;4 6 2];
[row,col] = size(MP);
for i= 1: row
    x = max(max(MP));
    [r,c] = find(MP==x);
    MP(r,:)=0;
    MP(:,c)=0;
    MP(r,c)=1;
end
MP

[Raja Zufar]

Thank you, my code really work now its so helpfull :)

[the cyclist]

Please see my answer, which points out that this solution is not valid for some input matrices.

(Or possibly I misunderstood what you wanted.)

Answer 2

[the cyclist]

Blatantly stealing ideas from Ameer's and Rajil's solutions here. But I think there are some potential issues with those, specifically:

• doing an in-place solution
• assuming that the original input matrix doesn't have elements that are less than 1

For example, I don't think those solutions will work on this input:

rng default
MP = rand(4)-0.5;

I think this solves both issues mentioned above:

[row,col] = size(MP);
MP_output = zeros(row,col);

for i= 1: row
    x = max(MP(:)); % If R2018b or later, could use   x = max(MP,[],'all');
    [r,c] = find(MP==x);
    MP_output(r,c) = 1;
    MP(r,:)=-Inf;
    MP(:,c)=-Inf;
end

The output you want is given by the variable MP_output.

[Raja Zufar]

Thanks sir for the new code :). I use "rand" only to assume the value of the matrix, the actual value of my matrix is big positive. and forgive me for making you confused

[the cyclist]

I'm glad the other solution is fine for you.

In general, good programming practice would be to either

• use an algorithm that works on more general inputs, OR
• make sure you comment your code, indicating the input requirement

That way, someone else who uses your code (or maybe just "future you") will not be confused why the algorithm doesn't work if they try on different input.

You may be thinking "I'm only going to use this code on this one small program, or homework, so I don't need to worry about this", but I think it is still worthwhile to practice these habits.

[Raja Zufar]

Im really thankfull for the advice because im new at matlab code. And i dont know if its okay im asking the question and put in like 300 line main.m file and 20 function code. I think it gonna make people who answering confuse

Answer 3

[Ameer Hamza]

Try this

MP = [8 9 1;
      3 5 7;
      4 6 2];

MPouput = zeros(size(MP));
for i=1:size(MP,1)
    [~, idx] = max(MP(i, :));
    MPouput(i, idx) = 1;
    MP(:, idx) = 0;
end

Result

>> MPouput
MPouput =
     0     1     0
     0     0     1
     1     0     0

[Raja Zufar]

Thanks sir for helping, i have alternative code for another project now :)