Remove the last comma in a string

Question

I have a data.frame. It looks like this:

name    state
Lily    NY
Tom     NY,NJ,
John    PA,NJ
David   SC,PA,NY,
Jim     FL,PA
......

There are more than 100 rows. I just want to remove the last comma in each string if there is. My goal is not to remove all the last character.

Answer 1

Use a regular expression? Assuming your data frame is DF:

DF$state <- gsub(",$", "", DF$state)

The regular expression ,$ means every comma that occurs at the end of a string. The command gsub replaces every instance of the first argument with the second argument (in this case, nothing) that occurs in the third argument (DF$state).

Answer 2

With R 3.6.0, we can also use trimws with whitespace parameter specifying the ,

DF$state <- trimws(DF$state, whitespace = ",")
DF$state
#[1] "NY"       "NY,NJ"    "PA,NJ"    "SC,PA,NY" "FL,PA"   

data

DF <- structure(list(name = c("Lily", "Tom", "John", "David", "Jim"
 ), state = c("NY", "NY,NJ,", "PA,NJ", "SC,PA,NY,", "FL,PA")),
 class = "data.frame", row.names = c(NA, -5L))