How to write this simple script correctly?

Question

Rita 2015-8-11

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评论： Rita 2015-8-11

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.

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Answer 1

Stephen23 2015-8-11

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编辑：Stephen23 2015-8-11

在 MATLAB Online 中打开

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

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Rita 2015-8-11

Thanks for your quick responses.

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Answer 2

Star Strider 2015-8-11

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https://ww2.mathworks.cn/matlabcentral/answers/233270-how-to-write-this-simple-script-correctly#answer_188959

在 MATLAB Online 中打开

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