Question

I have a 721 x 26 dataframe. Some rows have entries that are blank. It’s not NULL
or NA but just empty like the following. How can I delete those rows that have these kind of entries?

1         Y    N        Y          N            86.8
2         N    N        Y          N            50.0
3                                               76.8
4         N    N        Y          N            46.6
5         Y    Y        Y          Y            30.0

Answer 1

The answer to this question depends on how paranoid you want to be about the sort of things that might be in ‘blank’-appearing character strings. Here’s a fairly careful approach that will match the zero-length blank string "" as well as any string composed of one or more [[:space:]] characters (i.e. “tab, newline, vertical tab, form feed, carriage return, space and possibly other locale-dependent characters”, according to the ?regex help page).

## An example data.frame containing all sorts of 'blank' strings
df <- data.frame(A = c("a", "", "\n", " ", " \t\t", "b"),
                 B = c("b", "b", "\t", " ", "\t\t\t", "d"),
                 C = 1:6)

## Test each element to see if is either zero-length or contains just
## space characters
pat <- "^[[:space:]]*$"
subdf <- df[-which(names(df) %in% "C")] # removes columns not involved in the test
matches <- data.frame(lapply(subdf, function(x) grepl(pat, x))) 

## Subset df to remove rows fully composed of elements matching `pat` 
df[!apply(matches, 1, all),]
#   A B C
# 1 a b 1
# 2   b 2
# 6 b d 6

## OR, to remove rows with *any* blank entries
df[!apply(matches, 1, any),]
#   A B C
# 1 a b 1
# 6 b d 6