identifying entry elements in rows of logical matrix

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julian gaviria
julian gaviria 2023-1-25
评论： Dyuman Joshi 2023-1-27
I want to identifiy the entry elements (i.e., the first "1" value) in the rows of the following logical matrix
input_matrix = [1 1 1; 0 1 1; 0 0 0; 0 1 0];
the expected matrix would be the following:
output_matrix = [1 0 0; 0 1 0; 0 0 0; 0 1 0];
The position of the "entries" (first "1" values) in both input and output matrices is respected. Also, Further "1" values (following the entries) have been replaced with "0" values.
Thanks in advance for any hint.
  2 个评论
Dyuman Joshi
Dyuman Joshi 2023-1-26
编辑：Dyuman Joshi 2023-1-26
@julian gaviria Just a note -
My and Stephen's code did exactly what was asked.
You should have clarified what exactly you wanted, in your question statement. The comments on my code clearly indicated what the code does, and you should have picked up from them that it is not what you want to do and mentioned it in reply to that.
Nevertheless, @Stephen23 has already provided an answer for your query.
I will be deleting my solution.

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采纳的回答

Stephen23
Stephen23 2023-1-25
编辑：Stephen23 2023-1-26
Ran in:
A = [1,1,1;0,1,1;0,0,0;0,1,0]
A = 4×3
1 1 1 0 1 1 0 0 0 0 1 0
B = A .* (cumsum(A,2)==1) % replace .* with & to get a logical output
B = 4×3
1 0 0 0 1 0 0 0 0 0 1 0
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更多回答（1 个）

Fangjun Jiang
Fangjun Jiang 2023-1-25
Ran in:
in = [1 1 1; 0 1 1; 0 0 0; 0 1 0];
M=size(in,1);
temp=[zeros(M,1), in];
d=diff(temp,1,2);
out=(d==1)
out = 4×3 logical array
1 0 0 0 1 0 0 0 0 0 1 0
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Dyuman Joshi
Dyuman Joshi 2023-1-25
Ran in:
This wouldn't work if there is a 1 after a 0
in = [1 1 0 1; 0 1 1 1; 0 0 0 0; 0 0 1 0];
M=size(in,1);
temp=[zeros(M,1), in];
d=diff(temp,1,2);
out=(d==1)
out = 4×4 logical array
1 0 0 1 0 1 0 0 0 0 0 0 0 0 1 0

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