Search code examples
rnagsubcoercion

Is there a way to identify where NAs are introduced?

Recently went through my fairly large dataset and realized some foo decided to use commas. Trying to convert it all to numeric. Used a nice little gsub to get rid of those pesky commas, but I'm still finding NAs introduced by coercion. Is there a way to identify the location by column and row where those NAs are being introduced so I can see why that is occurring?

Solution

  • Use the is.na() function. Consider the following data frame, which contains NA values, as an example:

    > df <- data.frame(v1=c(1,2,NA,4), v2=c(NA,6,7,8), v3=c(9,NA,NA,12))
> df
  v1 v2 v3
1  1 NA  9
2  2  6 NA
3 NA  7 NA
4  4  8 12

    You can use is.na along with sapply to get the following result:

    > sapply(df, function(x) { c(1:length(x))[is.na(x)] })
$v1
[1] 3

$v2
[1] 1

$v3
[1] 2 3

    Each column will come back along with the rows where NA values occurred.