Reputation: 137
I have two a matrix where some of the cells within the matrices are NA and others are filled with a list of numbers. And what I need is a way to calculate the number of items within each list for each cell of the matrix.
Here is the matrix:
> matrix_1
[,1] [,2]
[1,] NA c(1001, 1002)
[2,] c(1001, 1003) NA
Here is what I am looking for:
[,1] [,2]
[1,] NA 2
[2,] 2 NA
The actual data set is much, much larger - so I am trying to avoid loops.
Here is the dput:
Matrix 1 = structure(list(NA, c(1001, 1003), c(1001, 1002), NA), .Dim = c(2L,
2L))
Upvotes: 2
Views: 86
Reputation: 79338
You could decide to do:
NA^is.na(matrix1) * lengths(matrix1)
[,1] [,2]
[1,] NA 2
[2,] 2 NA
or even:
`is.na<-`(lengths(matrix1), is.na(matrix1))
[,1] [,2]
[1,] NA 2
[2,] 2 NA
Upvotes: 1
Reputation: 872
It seems that your description of the question and the expected output are slightly different.
The number of items in a list element conaining a single NA
is 1, not NA. So the answer to this is:
matrix1=matrix(list(NA,c(1001,1003),c(1001,1002),NA),nrow=2)
answer=array(lengths(matrix1),dim=dim(matrix1))
answer
# [,1] [,2]
# [1,] 1 2
# [2,] 2 1
However, if you want to convert all the elements corresponding a single NA
entry to be NA
themselves (in agreement with your expected output), you can do the extra step:
answer[is.na(matrix1)]=NA
answer
# [,1] [,2]
# [1,] NA 2
# [2,] 2 NA
Note that elements of more-than-one item, of which some are NA
won't be detected by this last step... (you'd need to use answer[sapply(matrix1,function(x) any(is.na(x)))]=NA
instead).
Upvotes: 0
Reputation: 102680
Maybe you can try lengths
+ replace
like below
> replace(lengths(matrix_1),which(is.na(matrix_1)),NA)
[,1] [,2]
[1,] NA 2
[2,] 2 NA
Upvotes: 0