matrix question

[Eric yang <yang_eric9@yahoo.com>]

 

Dear members,

 

I have a simple matrix problem which is solvable using for-loops but as they're not particular efficient I would prefer not to use them.

 

Here is an example of what I'm trying to do. Suppose I have the following matrix

>my.matrix
          [,1]     [,2]     [,3]     [,4]     [,5]
 [1,] 19.35602 20.82310 18.71526 17.33000 20.71457
 [2,] 20.12000 21.12000 21.22000 17.33000 23.06444
 [3,] 20.12000 21.12000 21.22000 17.33000 21.34383
 [4,] 20.12000 21.12000 21.22000 17.33000 20.27115
 [5,] 20.12000 22.12000 21.22000 18.33000 20.03679
 [6,] 20.12000 22.12000 21.22000 18.33000 26.12412
 [7,] 20.12000 22.12000 21.22000 19.33000 19.84222
 [8,] 20.12000 23.12000 20.53322 19.33000 19.42392
 [9,] 20.12000 23.12000 18.52401 19.33000 21.56694
[10,] 20.12000 23.12000 21.66532 20.37692 18.93681
[11,] 20.12000 23.80764 18.67000 21.06952 21.97545
[12,] 20.12000 21.67629 18.67000 20.33678 20.90008
[13,] 20.12000 21.00464 18.67000 19.36164 18.38411

I want to create two additional matrices (or an array) related to this one. The first matrix counts (column by column) the number of consecutive repeatitions of a value for each column, i.e.

 >my.matrix1
      [,1] [,2] [,3] [,4] [,5]
 [1,]    1    1    1    4    1
 [2,]   12    3    6    4    1
 [3,]   12    3    6    4    1
 [4,]   12    3    6    4    1
 [5,]   12    3    6    2    1
 [6,]   12    3    6    2    1
 [7,]   12    3    6    3    1
 [8,]   12    3    1    3    1
 [9,]   12    3    1    3    1
[10,]   12    3    1    1    1
[11,]   12    1    3    1    1
[12,]   12    1    3    1    1
[13,]   12    1    3    1    1

and the other matrix defines the repeatition number within the sequence, i.e.

 >my.matrix2
      [,1] [,2] [,3] [,4] [,5]
 [1,]    1    1    1    1    1
 [2,]    1    1    1    2    1
 [3,]    2    2    2    3    1
 [4,]    3    3    3    4    1
 [5,]    4    1    4    1    1
 [6,]    5    2    5    2    1
 [7,]    6    3    6    1    1
 [8,]    7    1    1    2    1
 [9,]    8    2    1    3    1
[10,]    9    3    1    1    1
[11,]   10    1    1    1    1
[12,]   11    1    2    1    1
[13,]   12    1    3    1    1

I would appreciate any help in constructing my.matrix1 and my.matrix2 without the need for using for-loops.

 

Thanks in advance.

 

Regards

 

Eric

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