populate matrix columns based on a vector of index vector

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MatG 2020-6-12

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编辑： Stephen23 2020-6-12

I generate an 8x8 A matrix below. I also have an 8x1 vector B containing random integer numbers from 1 to 8. And, I have an 8x1 C vector containing numbers obtained below. How can I, for all rows of A, populate those columns of A starting at B to the end, with values of corresponding rows in C without going through a loop (i.e. vectorized).

A=rand(8);
B = randi([1 8], 8, 1);
C=-linspace(8,30,8)';

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KSSV 2020-6-12

Confused.....what out put you are expecting?

MatG 2020-6-12

Imagine

A = [

1 2 3 4 5

1 2 3 4 5]

And

B = [1 3 4 2 5]

C = [-10 -9 -5 -2 -1];

Then, I want A(1,B(1):end) = C(1), A(2,B(2):end) = C(2), ....

So I get:

A = [-10 -10 -10 -10 -10

1 2 -9 -9 -9

1 2 3 -5 -5

1 -2 -2 -2 -2

1 2 3 4 -1]

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Answer 1

Stephen23 2020-6-12

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编辑：Stephen23 2020-6-12

>> X = (1:5)>=B(:); % requires >=R2016b, for earlier versions replace >= with BSXFUN
>> [R,~] = find(X);
>> A(X) = C(R)
A =
  -10  -10  -10  -10  -10
    1    2   -9   -9   -9
    1    2    3   -5   -5
    1   -2   -2   -2   -2
    1    2    3    4   -1