Finding NAs in DF

building on the previous responses, does this give you what you want:
x
A  B
1  1  1
2  2 NA
3 NA NA
4 NA  4
# determine where the NAs are
row.na <- apply(x, 1, is.na)
# now convert to list of columns with NAs
apply(row.na, 2, function(a) paste(colnames(x)[a], collapse = ','))
[1] ""    "B"   "A,B" "A"

On Mon, Jan 17, 2011 at 5:01 AM, Johannes Graumann
Hi,

What is an efficient way to take this DF

? ? ? ?data.frame(A=c(1,2,NA,NA),B=c(1,NA,NA,4))

and get
? ? ? ?c(NA,"TWO","BOTH","ONE")

as the result, where NA corresponds to a row without "NA"s, TWO indicates NA
in the second and ONE in the first column.

Thanks for any pointers.

Joh

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What is the problem that you are trying to solve?

Finding NAs in DF

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