Getting the rownumbers for all NA values of a column-CodePudding

I have data as follows:

df <- as.data.frame(c(1,2,NA,4,5))
names(df)[1] <- "first_column"

  first_column
1            1
2            2
3           NA
4            4
5            5

I would like to get all the row numbers for which first_column is NA, so 3

I found ways to look up other values, i.e. which(grepl(2, df$first_column)) but not NA. Including NA values is apparently quite cumbersome (link). Is there an easier way to do this?

Any ideas?

CodePudding user response：

We could use which with is.na

which(is.na(df))

[1] 3

CodePudding user response：

which(is.na(df$first_column)==T)