hi every one, i need to ask a question, thank you

if i have a row vector like this A=[ 0 1 1 1 0 0 1 1 0 1 ]

and another vector B=[ 1 2 3 4 5 6 ]

and i need to put the element of B in order in A when the element is equal to 1

so if it can possibile i need to return a vector with the dimensions of B like this [ 0 1 2 3 0 0 4 5 0 6 ] , how can i do it if it's possibile to do it in matlab

thank you

Answer 1

[Image Analyst]

Try this:

A=[ 0 1 1 1 0 0 1 1 0 1 ]
B=[ 1 2 3 4 5 6 ] 
out = A % Initialize
out(logical(A)) = B % Assign B to "1" locations in A

It give you what you asked for.

Answer 2

[Matt J]

result=sparse(1,find(A),B)

Answer 3

[Catalytic]

A=double(A);
A(logical(A))=B;

Answer 4

[Matt J]

 [i,j]=find(A(:));
 result=accumarray([i,j],B(:),size(A.')).'

[Image Analyst]

I'm not understanding why this was accepted or even how it works.

My code below

A=[ 0 1 1 1 0 0 1 1 0 1 ];
B=[ 1 2 3 4 5 6 ];
out = A; % Initialize
out(logical(A)) = B % Assign B to "1" locations in A

gives

out =

0 1 2 3 0 0 4 5 0 6

However Matt's code

A=[ 0 1 1 1 0 0 1 1 0 1 ];
B=[ 1 2 3 4 5 6 ];
result=accumarray(find(A),B(:),size(A))

gives

Error using accumarray

Second input VAL must be a vector with one element for each row in SUBS, or a scalar.

Error in test3 (line 3)

result=accumarray(find(A),B(:),size(A))

What am I not getting?

[Matt J]

I've debugged the accumarray solution, though I'm not sure why it was preferred over this one. That was the first answer offered and works straight out of the box.

[Image Analyst]

I think it's because the poster did not see what she wanted to see. So instead of seeing:

0 1 2 3 0 0 4 5 0 6

like she asked for, you see

result =

(1,2) 1

(1,3) 2

(1,4) 3

(1,7) 4

(1,8) 5

(1,10) 6

[mina massoud]

sorry i accept it by mistake , now i accept your answer that is the best answer

thank's very much for all of you, i really appraciate it