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rmatrixsumapplyrollapply

R Sum complete cases of two columns

How can I sum the number of complete cases of two columns?

With c equal to:

      a  b
[1,] NA NA
[2,]  1  1
[3,]  1  1
[4,] NA  1

Applying something like 

rollapply(c, 2, function(x) sum(complete.cases(x)),fill=NA)

I'd like to get back a single number, 2 in this case. This will be for a large data set with many columns, so I'd like to use rollapply across the whole set instead of simply doing sum(complete.cases(a,b)).

Am I over thinking it?

Thanks!

Solution

  • You can calculate the number of complete cases in neighboring matrix columns using rollapply like this:

    m <- matrix(c(NA,1,1,NA,1,1,1,1),ncol=4)
#     [,1] [,2] [,3] [,4]
#[1,]   NA    1    1    1
#[2,]    1   NA    1    1

library(zoo)

rowSums(rollapply(is.na(t(m)), 2, function(x) !any(x)))
#[1] 0 1 2