Overwriteing select values in multidimensional array

Hello All,

I'm having issues with changing select values of an array. I'm able to create a logical matrix (loc#) that meets my conditions and then get an array with the values I want, (val). However, I can't think/google a way to contine to change values in val, (ex. val==0), with out overwriting all the values in val.

tmp1 = (rand(5,5,5)-.5)*10;
tmp2 = (rand(5,5,5)-.5)*10;

loc1 = tmp1 > 0;
val = tmp1.*loc1;

loc2 = tmp2 > 0;
val(loc2) = tmp2.*loc2;
% val(val) = tmp2.*loc2;
% val(val==0) = tmp2.*loc2;
% val(:) = tmp2.*loc2;

Any help with this would be appreciated. Thanks in advance

Answer 1

[Dyuman Joshi]

tmp1 = (rand(5,5,5)-.5)*10;
tmp2 = (rand(5,5,5)-.5)*10;

loc1 = tmp1 > 0;
%This is a shortcut way of logical indexing
val = tmp1.*loc1;

loc2 = tmp2 > 0;
%Use logical indexing
val(loc2) = tmp2(loc2);

You can do logical indexing for both conditions -

%Preallocate the output array
val = zeros(size(tmp1)); %you can preallocate NaN as well

loc1 = tmp1 > 0;
val(loc1) = tmp1(loc1);

loc2 = tmp2 > 0;
val(loc2) = tmp2(loc2);

Answer 2

[dpb]

You're just making it harder than it is...

tmp1 = (rand(5,5,5)-.5)*10;
loc1 = tmp1 > 0;
tmp1(loc1)=123456;       % Use the force (aka addressing vector), Luke!!!

<Read all about logical addressing here>