Repetition of elements in a matrix

Question

Danish Nasir 2021-9-4

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https://ww2.mathworks.cn/matlabcentral/answers/1446644-repetition-of-elements-in-a-matrix

评论： Walter Roberson 2021-9-4

Suppose i have a matrix A= [25 21 ] . I want to repeat elements by 4 and 2 times respectively. Repeat=[4 2]. However the repeated values will be in proportion i.e. Proportion=[8 17]. The sum of proportion repeated element will be equal to A matrix elements. It means that final matrix will be B= [8 8 8 1 17 4].

(25=8+8+8+1 , 21=17+4 )

Pls suggest code to generate matrix B

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Answer 1

Walter Roberson 2021-9-4

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https://ww2.mathworks.cn/matlabcentral/answers/1446644-repetition-of-elements-in-a-matrix#answer_780764

在 MATLAB Online 中打开

A = [25 21 ]
A = 1×2
    25    21
Repeat = [4 2]
Repeat = 1×2
     4     2
Proportion = [8 17]
Proportion = 1×2
     8    17
leftover = A - Proportion .* (Repeat-1);
toRepeat = reshape([Proportion; leftover],1,[]);
repeatCount = reshape([Repeat-1; ones(1,length(Repeat))],1,[]);
B = repelem(toRepeat, repeatCount)
B = 1×6
     8     8     8     1    17     4

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Danish Nasir 2021-9-4

It nearly solved my problem. I just want to add one complexity in the problem. There is a 3rd element in the matrix which i do not want to propotionate

A=[25 21 30]

Repeat=[4 2 1]

Proportion=[8 17 30].

B=[8 8 8 1 17 4 30]

Can you suggest how to generate B?

Walter Roberson 2021-9-4

在 MATLAB Online 中打开

The code already handles that.

A = [25 21 30]
A = 1×3
    25    21    30
Repeat = [4 2 1]
Repeat = 1×3
     4     2     1
Proportion = [8 17 30]
Proportion = 1×3
     8    17    30
leftover = A - Proportion .* (Repeat-1);
toRepeat = reshape([Proportion; leftover],1,[]);
repeatCount = reshape([Repeat-1; ones(1,length(Repeat))],1,[]);
B = repelem(toRepeat, repeatCount)
B = 1×7
     8     8     8     1    17     4    30