How to skip a paste() argument when its value is NA in R

Question

I have a data frame with the columns city, state, and country. I want to create a string that concatenates: "City, State, Country". However, one of my cities doesn't have a State (has a NA instead). I want the string for that city to be "City, Country". Here is the code that creates the wrong string:

# define City, State, Country
  city <- c("Austin", "Knoxville", "Salk Lake City", "Prague")
  state <- c("Texas", "Tennessee", "Utah", NA)
  country <- c("United States", "United States", "United States", "Czech Rep")
# create data frame
  dff <- data.frame(city, state, country)
# create full string
  dff["string"] <- paste(city, state, country, sep=", ")

When I display dff$string, I get the following. Note that the last string has a NA,, which is not needed:

> dff["string"]
                               string
1        Austin, Texas, United States
2 Knoxville, Tennessee, United States
3 Salk Lake City, Utah, United States
4               Prague, NA, Czech Rep

What do I do to skip that NA,, including the sep = ", ".

There is a general discussion of suppressing NAs in paste [here](http://stackoverflow.com/questions/13673894/suppress-nas-in-paste), should you have more than one column containing NAs. — JWilliman, Sep 08 '15 at 03:09

thelatemail · Accepted Answer · 2014-04-04T06:39:53.587

10

The alternative is to just fix it up afterwards:

gsub("NA, ","",dff$string)

#[1] "Austin, Texas, United States"       
#[2] "Knoxville, Tennessee, United States"
#[3] "Salk Lake City, Utah, United States"
#[4] "Prague, Czech Rep"

Alternative #2, is to use apply once you have your data.frame called dff:

apply(dff, 1, function(x) paste(na.omit(x),collapse=", ") )

edited Apr 04 '14 at 06:39

answered Apr 04 '14 at 05:29

thelatemail

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I was going to give a two-barrelled answer, but *somebody* took the first part for their own answer ;-) – thelatemail Apr 04 '14 at 05:35
Actually, I'd be interested in the performance of each, as well as possible gotcha's.... – A5C1D2H2I1M1N2O1R2T1 Apr 04 '14 at 07:07

score 7 · Answer 2 · answered Sep 20 '21 at 14:24

Late to the party, but unite provides a one-step approach:

dff %>% unite("string", c(city, state, country), sep=", ", remove = FALSE, na.rm = TRUE)

                              string           city     state       country
1        Austin, Texas, United States         Austin     Texas United States
2 Knoxville, Tennessee, United States      Knoxville Tennessee United States
3 Salk Lake City, Utah, United States Salk Lake City      Utah United States
4                   Prague, Czech Rep         Prague      <NA>     Czech Rep

How to skip a paste() argument when its value is NA in R

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