R can't convert NaN to NA

Question

I have a data frame with several factor columns containing NaN\'s that I would like to convert to NA\'s (the NaN seems to be a problem for

Answer 1

EDIT:

Gavin Simpson in comments reminds me that, in your situation, there are much easier ways to convert what is really an "NaN" to an "NA":

tester1 <- gsub("NaN", "NA", tester1)
tester1
# [1] "2"  "2"  "3"  "4"  "2"  "3"  "NA"

---

Solution:

To detect which elements of the character vector are NaN, you need to convert the vector to a numeric vector:

tester1[is.nan(as.numeric(tester1))] <- "NA"
tester1
[1] "2"  "2"  "3"  "4"  "2"  "3"  "NA"

Explanation:

There are a couple of reasons that this isn't working as you expect it to.

First, although NaN stands for "Not a Number", it does have class "numeric", and only makes sense inside of a numeric vector.

Second, when it is included in a character vector, the symbol NaN is silently converted to the character string "NaN". When you then test it for nan-ness, the character string returns FALSE:

class(NaN)
# [1] "numeric"
c("1", NaN)
# [1] "1"   "NaN"
is.nan(c("1", NaN))
# [1] FALSE FALSE