Filter value from multiple columns

I have the following array named "tNino1_2"

I want to filter the value equal to 1 from columns 20, 21, 22, 23 and 24

The script I'm using is below:

xcol=20:1:24
idx=tNino1_2(tNino1_2(:,xcol)==1,:)

The logical indices in position 1 contain a true value outside of the array bounds.

[Voss]

What do you mean by "filter"? What exactly do you want to do when you find a 1 somewhere in columns 20-24? Replace the 1 with NaN or some other value? Remove the entire row from the matrix? Extract those rows into another variable? Etc.

[Augusto Gabriel da Costa Pereira]

Actually my goal is to find the values equal to 1 in columns 20 to 24

[Dyuman Joshi]

Do you want to find the position (both row and column values) of elements equal to one between columns 20 to 24?

[Augusto Gabriel da Costa Pereira]

@Dyuman Joshi exactly

Answer 1

[Mathieu NOE]

hello

I assumed you want all the rows where there is at least one 1 in the columns 20 to 24

xcol=20:1:24;

[r,c] = find(tNino1_2(:,xcol)==1);
[ru,ia,ic] = unique(r);
out = tNino1_2(ru,:);

[Augusto Gabriel da Costa Pereira]

This script is exactly what I wanted, it worked perfectly.

Thank you Mathieu, you are accurate as always.

[Mathieu NOE]

hello Augusto

as always, my pleasure !

Answer 2

[Voss]

load tNino1_2

"find the values equal to 1 in columns 20 to 24"

[r,c] = find(tNino1_2(:,20:24) == 1)

r = 28×1

96 97 98 107 164 174 107 164 174 175

c = 28×1

1 1 1 1 1 1 2 2 2 2

r is rows and c is columns. Of course, c is relative to columns 20-24 only, so c = 1 means column 20 of the original matrix, c = 2 means column 21, etc.

You can add 19 to c to get the locations of the 1s in the original matrix

c = c+19

c = 28×1

20 20 20 20 20 20 21 21 21 21

Confirm that the elements at those locations are all 1s:

temp = tNino1_2(sub2ind(size(tNino1_2),r,c))

temp = 28×1

1 1 1 1 1 1 1 1 1 1

all(temp == 1)

ans = logical
   1

[Augusto Gabriel da Costa Pereira]

thank you, this script is perfect to identify the rows and columns of the condition I entered