Finding out the minimum value position of a matrix

I have a matrix (a=[1 2 3 4 5 10;2 3 5 6 1 12;2 6 4 5 7 16;10 2 1 4 5 20;2 3 1 4 9 12])

I want to find out the minimum value postion in 2nd row from 1st to 3rd column

I have written this code

[r1,c1]=find(a(i,1:6)==min(a(i,4:6)))

But insted of showing the position as 2nd row 1st column it is showing like this

i1 =

1

j1 =

1

can you please help me where i have done the mistake

Answer 1

[Mathieu NOE]

hello

try this

your answer is in r_final and c_final

a=[1 2 3 4 5 10;2 3 5 6 1 12;2 6 4 5 7 16;10 2 1 4 5 20;2 3 1 4 9 12]

rr = 2;
cc = (1:3);
[r,c] = find(min(a(rr,cc)));% r and c referenced to rr and cc

r_final = rr(r);
c_final = cc(c);

[Stephan]

What if we want to find the min of row 5 in col 1:3 - which is 1 and is at pos. [5,3]:

a=[1 2 3 4 5 10;2 3 5 6 1 12;2 6 4 5 7 16;10 2 1 4 5 20;2 3 1 4 9 12]

a = 5×6

1 2 3 4 5 10 2 3 5 6 1 12 2 6 4 5 7 16 10 2 1 4 5 20 2 3 1 4 9 12

rr = 5;
cc = (1:3);
[r,c] = find(min(a(rr,cc)));% r and c referenced to rr and cc

r_final = rr(r)

r_final = 5

c_final = cc(c)

c_final = 1

This appears to be wrong

[Mathieu NOE]

My bad

find is anyway not needed here - forgot that

this is a better code - tested here with your inputs

r_final = 5

c_final = 3

a=[1 2 3 4 5 10;2 3 5 6 1 12;2 6 4 5 7 16;10 2 1 4 5 20;2 3 1 4 9 12]

rr = 5;
cc = (1:3);
b = a(rr,cc);
[value, index] = min(b(:));
[r,c] = ind2sub(size(b), index);% r and c referenced to rr and cc

r_final = rr(r);
c_final = cc(c);

[Mathieu NOE]

NB this code works also with multiple rows and multiple cols

a=[1 2 3 4 5 10;2 3 5 6 1 12;2 6 4 5 7 16;10 2 2 4 5 20;2 3 1 4 9 12]

rr = (4:5);
cc = (1:3);
b = a(rr,cc);
[value, index] = min(b(:));
[r,c] = ind2sub(size(b), index);% r and c referenced to rr and cc

r_final = rr(r)
c_final = cc(c)

Answer 2

[Stephan]

a=[1 2 3 4 5 10;2 3 5 6 1 12;2 6 4 5 7 16;10 2 1 4 5 20;2 3 1 4 9 12]

a = 5×6

1 2 3 4 5 10 2 3 5 6 1 12 2 6 4 5 7 16 10 2 1 4 5 20 2 3 1 4 9 12

% Here for the example row = 5, col = 1...3
ii = 5; % wanted row
range = 1:3; % column range
[r,c] = find(a==(min(a(ii,range)))); % all values that are equal the min of row 2, col 1:3
pos = [r(r==ii), c(r==ii)] % the correct position for the wanted row

pos = 1×2

5 3