Replace all string instances of "NULL" with actual NULL or NA in a data frame

Question

I wondered if there was a one liner where I could replace all instances of string "NULL" in a DF across multiple fields with just NULL or NA?

exampledf <- data.frame(
  a = c("NULL", "1/1/20", "2/28/20"),
  b = c("NULL", "blah", "ha"),
  c = c("NULL", "NULL", "cat")
)

Is there a one liner that would replace "NULL" across the entire df with NULL or NA?

Also see [1](https://stackoverflow.com/q/51449243/5325862), [2](https://stackoverflow.com/q/56928827/5325862), [3](https://stackoverflow.com/q/27909000/5325862) — camille, May 15 '21 at 16:08
If that post solves it, you should be able to mark your own question as a duplicate of that one — camille, May 15 '21 at 19:16

score 4 · Answer 1 · answered May 15 '21 at 18:13

4

Using dplyr

library(dplyr)
exampledf <- exampledf %>%
      mutate(across(everything(), na_if, "NULL"))

answered May 15 '21 at 18:13

akrun

Elia · Accepted Answer · 2021-05-15T16:11:42.193

2

Just do this:

exampledf[exampledf=="NULL"] <- NA

or with dplyr

exampledf <- exampledf %>% replace(exampledf == "NULL", NA)

edited May 15 '21 at 16:11

answered May 15 '21 at 15:51

Elia

Thanks! Leaving open for a while in case anyone has a tidyverse approach could use within a pipe `exampledf %>%` – Doug Fir May 15 '21 at 16:03

score 1 · Answer 3 · answered May 15 '21 at 23:01

1

We can use replace like below

> replace(exampledf, exampledf == "NULL", NA)
        a    b    c
1    <NA> <NA> <NA>
2  1/1/20 blah <NA>
3 2/28/20   ha  cat

answered May 15 '21 at 23:01

ThomasIsCoding

3 Answers3