[R] consecutive numbering of elements in a matrix

[Dimitris Rizopoulos]

one approach is the following:

B <- cbind(c(1:6, NA), c(1:3, NA,NA,NA, 4), c(1:3, NA,NA, 4,5))
matrix(B[order(col(B), B)], nrow(B), ncol(B))


I hope it helps.

Best,
Dimitris


Jim Bouldin wrote:
>> And think about the fact that row(A) and apply(is.na(A), 2, cumsum)  
>> will be identical in the case where there are no NAs, so their  
>> difference would be a zero matrix. Double negativism strikes again....  
>> not(is.na) == "is"
> 
> OK I see it now--thanks.  I was interpreting the apply function incorrectly
> in terms of what it was summing.
> 
>> You cannot have unequal length columns in a matrix. Only a list is  
>> able to handle that task. So we need a more clear description of what  
>> you expect, preferably typed out in full so we can "see" it.
> 
> Given a matrix B like before, which has NAs mixed with integers in all
> columns, where those NAs may occur anywhere within the columns, and where
> the integers within a column are always consecutive and increasing: 
> 
>> B
>      [,1] [,2] [,3] ...etc
> [1,]    1    1    1
> [2,]    2    2    2
> [3,]    3    3    3
> [4,]    4   NA   NA
> [5,]    5   NA   NA
> [6,]    6   NA    4
> [7,]    NA   4    5
> etc
> 
> I would like to create a new matrix, in which all NAs that occur BETWEEN
> consecutive integers are removed, and the integers which follow such NAs
> are moved "up" in the column to replace them.  NAs which occur near the
> bottom of each column, and are NOT followed by more integers can be
> retained without problem.  Empty spaces that might result from this
> process, near the column bottoms as the integers are moved up, would need
> to be replaced by NAs so that equal numbers of entries are maintained in
> each row, hence still allowing a matrix to exist:
> 
> If B above were in fact the complete matrix, the desired result would thus be:
> 
>      [,1] [,2] [,3] etc
> [1,]    1    1    1
> [2,]    2    2    2
> [3,]    3    3    3
> [4,]    4    4    4
> [5,]    5   NA    5
> [6,]    6   NA   NA
> [7,]    NA  NA   NA
> etc
> 
> In other words, all integers of a particular value in the original matrix
> need to be placed on the same row of a new matrix, and all "empty" values
> replaced with NA.  I hope that explains it well enough, but will try again
> if not. Thanks again for any help.
> Jim
> 
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-- 
Dimitris Rizopoulos
Assistant Professor
Department of Biostatistics
Erasmus University Medical Center

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