Matrix Manipulation based on index

Hi all,

I would appreciate assistance to do the following:

I have the following vector

v=[1
1
2
3
3
3
3
3
3
4
4
4
4
]'

each number of this vector is an index value that repeats a certain number of times, or not at all. I would like to use as a recipe to modify the following matrix M. The matrix M contains unique rows that pertain to a particular index value in the vector v as such:

M=
1  0.0127  5.0127
2  0.00266  5.00266
3  0.00263  5.00263
4  0.00266  5.00266

I would like to use the sequence of unique indices in v as a recipe to repeat the rows in the matrix M and produce the following matrix P:

P=
1  0.0127  5.0127
1  0.0127  5.0127
2  0.00266  5.00266
3  0.00263  5.00263
3  0.00263  5.00263
3  0.00263  5.00263
3  0.00263  5.00263
3  0.00263  5.00263
3  0.00263  5.00263
4  0.00272  5.00272
4  0.0129  5.0129
4  0.0129  5.0129
4  0.0129  5.0129

Notice the rows of matrix P are repeated in the exact sequence as listed in the index vector v.

I would greatly appreciate any help.

thank you,

Mark

Answer 1

[Azzi Abdelmalek]

P=M(v,:);