[R] How to count the number of NAs in each column of a df?

[Michael Kubovy]

Dear Jim (25 minutes!), Richard (27 minutes!), and Chuck,

Thanks to your hints, I have come up with what I hope is a pithy  
idiom that drops columns of a dataframe (df) in which the number of  
NAs is > (e.g.) 30.

tmp <- df
tmp <- tmp[, which(as.numeric(colSums(is.na(tmp))) > 30)]
df <- tmp

I wonder if we have a place to keep R programming idioms (which  
probably get unnecessarily reinvented). Is the R-Wiki suitable?
_____________________________
Professor Michael Kubovy
University of Virginia
Department of Psychology
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