How to loop through an n x n matrix and replace values in MATLAB?

Question

I have an n x n matrix in MATLAB. I am trying to iterate through each row and column of this matrix. If the value in each element is higher than a certain threshold, I want to replace that element with a 1. If the value in each element is lower than a certain threshold, I want to replace that element with a 0.

I am trying to use two for loops, but it's not leading me anywhere.Any suggestions?

Your answer is [here](https://stackoverflow.com/q/32379805/5211833) — Adriaan, Oct 19 '18 at 20:09

SecretAgentMan · Answer 1 · 2018-10-19T21:02:21.647

1

I suggest logical indexing.

A = randi([1 20],6,6);
Threshhold = 13;
A(A<Threshhold) = 0;
A(A>=Threshhold) = 1;

Before:

>> A = randi([1 20],6,6)
A =
     7     1    20     3     2    15
    16    13    11     3    11     7
     5     2     1     5    10    16
     5    14     8    14    11     8
    16    11     7    20    20    17
    10     1     2    10     6    12

After:

>> A
A =
     1     0     0     0     1     0
     0     0     1     0     0     0
     0     0     0     1     0     0
     1     1     1     0     1     1
     0     0     0     1     0     0
     0     0     0     0     0     0

Hope that helps.

Update:
Per @Cris Luengo from comments, Other approaches include A=double(A>=Threshold) or equivalently A=+(A>=Threshold).

edited Oct 19 '18 at 21:02

answered Oct 19 '18 at 20:44

SecretAgentMan

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Might as well do `A=double(A>=Threshold)`. Or equivalently `A=+(A>=Threshold)`. – Cris Luengo Oct 19 '18 at 20:58
Thanks @CrisLuengo, hadn't seen those approaches before. Updated the answer to include with attribution. – SecretAgentMan Oct 19 '18 at 21:00

How to loop through an n x n matrix and replace values in MATLAB?

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