How to write this simple script correctly?

Hi I have

 s=[1 0 1;0 0 0]; 
 b=[2 3 4];

I would like to have this as a result

 c=[nan 3 nan;2 3 4]

I mean replace 1 by nan and o by b.

 for r= 1:3
    s_ind = find(s(:,r) == 1);
    s(s_ind)=nan;
    m(:,r)=s
    a_ind = find(s(:,r) == 0);
    % I don't know how to replace for 0 from matrix b??
 end

any help would be appreciated in advance.

Answer 1

[Stephen23]

Simply using logical indexing:

>> s = [1,0,1;0,0,0];
>> b = [2,3,4];
>> out = repmat(b,size(s,1),1);
>> out(s==1) = NaN
out =
   NaN     3   NaN
     2     3     4

[Rita]

Thanks for your quick responses.

Answer 2

[Star Strider]

You can use logical indexing, although you need two separate steps to assign the elements of ‘b’ and ‘NaN’ to ‘c’ because you have two separate conditions.

One possibility:

s=[1 0 1;0 0 0]; 
b=[2; 3; 4];
mb = repmat(b', 2, 1);              % Create Matrix Matching ‘s’ From ‘b’
c = s;                              % Create ‘c’
c(~c) = mb(~c);                     % Assign Elements Of ‘mb’ To Zero Elements Of ‘c’
c(c==1) = NaN;                      % Assign ‘NaN’ To ‘c’ = 1