replace row value in COL2 by NA where other COL3 value is NA in R

Question

Hello I have a dataframe such as:

COL1 COL2 COL3
A    12   32
B    NA   NA
C    NA   NA
D    0    NA
E    21   90
F    0    NA 

and I would like to replace all COL2 values by NA where COL3 value is NA

Here I should get

   COL1 COL2 COL3
    A    12   32
    B    NA   NA
    C    NA   NA
    D    NA   NA
    E    21   90
    F    NA   NA 

So far I tried:

df$COL2[is.na(df$COL3)] <- NA 

but it does not seem to work

Answer 1

Try this:

library(tidyverse)

df %>% mutate(COL2 = ifelse(is.na(COl3), NA, COL2))

Answer 2

# your data
COL1 <- c("A","B","C","D","E","F")
COL2 <- c(12, NA, NA, 0, 21, 0)
COL3 <- c(32, NA, NA, NA, 90, NA)

# create df
df <- cbind.data.frame(COL1, COL2, COL3)

# replacing COL2 with NA when COL3 = NA
df$COL2 <- ifelse(is.na(df$COL3), df$COL3, df$COL2)