r - Determine the number of NA values in a column

Question

I want to count the number of NA values in a data frame column. Say my data frame is called df, and the name of the column I am considering is col. The way I have come up with is following:

sapply(df$col, function(x) sum(length(which(is.na(x)))))  

Is this a good/most efficient way to do this?

Answer 1

You're over-thinking the problem:

sum(is.na(df$col))