Octave: find the minimum value in a row, and also it's index

Question

How would one find the minimum value in each row, and also the index of the minimum value?

octave:1> a = [1 2 3; 9 8 7; 5 4 6]
a =

   1   2   3
   9   8   7
   5   4   6

Winded

You must know that Octave and MATLAB are very similar. This is why I would suggest looking in the corresponding MATLAB documentation when having a difficulty. – Amphictyon

Almost every question asked here could be found in some doc somewhere. That's a poor reason to vote down a useful question. – Synopsis

FYI The octave doc help min says "If called with one input and two output arguments, min also returns the first index of the minimum value(s). Example [x, ix] = min ([1, 3, 0, 2, 0])" – Beutler

Answer 1

This is hard to find in the documentation. https://www.gnu.org/software/octave/doc/v4.0.3/Utility-Functions.html

octave:2> [minval, idx] = min(a, [], 2)
minval =

   1
   7
   4

idx =

   1
   3
   2

Winded

hum.... If you type >help min in octave... You see Built-in Function: min (X, [], DIM) and also a long, detailed explanation that explains what you want. So, not hard to find :p – Malamut

Not to mention doc min. A Google search on octave min also took me right to the link you posted. – Humanize

IMHO, the documentation for Octave needs more examples for larger matrices with >1 dimension, the example in the documentation is for one row vector. – Winded

Answer 2

If A is your matrix, do:

[colMin, row] = min(A);
[rowMin, col] = min(A');

colMin will be the minimum values in each row, and col the column indexes. rowMin will be the minimum values in each column, and row the row indexes.

To find the index of the smallest element:

[colMin, colIndex] = min(min(A)); 
[minValue, rowIndex] = min(A(:,colIndex))

Congener

Answer 3

Suppose X is a matrix
row, col = Row and Column index of minimum value

[min_value, column_index] = min(X(:))
[row, col] = ind2sub(size(X),column_index)

Pennyworth

Answer 4

Given a matrix A of size m x n, you need to find the row number for the smallest value in the x column.

---

e.g A is 64x3 sized;

search_column = 3; 

[val,row] = min(results(:,search_column),[],1);

#row has the row number for the smallest value in the 3rd column.

Get the values for the first and second columns for the smallest row value

column1_value = A(row,1);
column2_value = A(row,2);

Laddy