How to assign Nans to specific column, not entire row

Hello!

I am trying to assign NaNs to values under 0.95, but only for the rows in column 4, not all of the columns.

Before, I used:

ZB1array = table2array(ZB1);
idx = ZB1array(:,4) < 0.95;
ZB1array(idx,: ) = NaN;

This successfully assigned NaNs, but to the entire row. In order to assign them to rows only in column 4 I tried:

ZB1array(idx, ZB1array(:,4)) = NaN;

But this returns the error 'Index in position 2 is invalid. Array indices must be positive integers or logical values.'

Does anyone know what I should do? Thanks!

Answer 1

[Scott MacKenzie]

Your first attempt was almost correct. Here's the fix:

ZB1array = rand(5,5) % test data

ZB1array = 5×5

0.7621 0.6576 0.7379 0.1125 0.0982 0.5320 0.2791 0.8808 0.4043 0.0584 0.5336 0.4350 0.4302 0.1737 0.6654 0.7437 0.6955 0.5260 0.9517 0.3347 0.8565 0.0006 0.9451 0.0728 0.1189

idx = ZB1array(:,4) < 0.95; 
ZB1array(idx,4) = NaN % must specify column 4

ZB1array = 5×5

0.7621 0.6576 0.7379 NaN 0.0982 0.5320 0.2791 0.8808 NaN 0.0584 0.5336 0.4350 0.4302 NaN 0.6654 0.7437 0.6955 0.5260 0.9517 0.3347 0.8565 0.0006 0.9451 NaN 0.1189

[Tanika Bawa]

Oh my goodness thanks so much works perfectly!

[Scott MacKenzie]

@Tanika Bawa, you're welcome. Glad to help.