Find names of columns which contain missing values

Question

I want to find all the names of columns with NA or missing data and store these column names in a vector.

# create matrix
a <- c(1,2,3,4,5,N         


        

Answer 1

Like this?

colnames(mymatrix)[colSums(is.na(mymatrix)) > 0]
# [1] "aa" "ee"