Replace String in one column from another string in different column based on a flag

Question

Let's assume I have a dataset like this one:

df1 = data.frame(Name=c("<HELLO>_World","World","HELLO_<WORLD>"),
                 Generic=c("<HELLO>","<HELLO>","<WORLD>"),
                 Substitution = c("hello1","world","world1"),
                 Flag = c("Yes","No","Yes"))

Now, based on the flag, I'd like to obtain the replacement in the "Name" column of the string in the substitution one, In the end the dataframe should look like this:

final <- data.frame(Name=c("hello1_World","world","HELLO_world1"))

I've tried with something like this:

index <- df1$Flag == "Yes"
df1$Name[index] <- gsub(df1$Generic[index],df1$Substitution[index])

Maybe it should be done in a new column (also acceptable)

Wimpel · Accepted Answer · 2022-03-24 11:20:49Z

2

library(tidyverse)
df1 %>%
  mutate(new_name = ifelse( 
    Flag == "Yes",
    unlist(purrr::pmap(list(x = Generic, y = Substitution, z = Name), 
                       ~ gsub(..1, ..2, ..3))),
    Name))

#             Name Generic Substitution Flag     new_name
# 1: <HELLO>_World <HELLO>       hello1  Yes hello1_World
# 2:         World <HELLO>        world   No        World
# 3: HELLO_<WORLD> <WORLD>       world1  Yes HELLO_world1

answered Mar 24, 2022 at 11:20

Wimpel

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1 Comment

shirewoman2 Over a year ago

How did you know to call the arguments in the list x, y, and z and then the arguments in gsub ..1, ..2, and ..3? Is there a variation on pmap -- maybe pmap_dfr?? -- that would eliminate the need for "unlist"? I find purrr really confusing.

Allan Cameron · Accepted Answer · 2022-03-24 11:22:07Z

0

In base R:

df1$result <- Map(function(flag, str, replace, sub) {
  if(flag == 'No') return(str)
  else gsub(sub, replace, str, fixed = TRUE)
}, flag = df1$Flag, str = df1$Name, replace = df1$Substitution, sub = df1$Generic)

df1
#>            Name Generic Substitution Flag       result
#> 1 <HELLO>_World <HELLO>       hello1  Yes hello1_World
#> 2         World <HELLO>        world   No        World
#> 3 HELLO_<WORLD> <WORLD>       world1  Yes HELLO_world1

answered Mar 24, 2022 at 11:22

Allan Cameron

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