Question

I am attempting to set a column in a dataframe equal to either ‘US’ or ‘Foreign’, depending on country. I believe the proper way to do so is to write a function, then use sapply to actually update the dataframe. This is the first time I’ve attempted something like this in R – in SQL, I would have just written an UPDATE query.

Here is my dataframe:

str(clients)
'data.frame':   252774 obs. of  4 variables:
 $ ClientID     : Factor w/ 252774 levels "58187855","59210128",..: 19 20 21 22 23 24 25 26 27 28 ...
 $ Country          : Factor w/ 207 levels "Afghanistan",..: 196 60 139 196 196 40 40 196 196 196 ...
 $ CountryType     : chr  "" "" "" "" ...
 $ OrderSize        : num  12.95 21.99 5.00 7.50 44.5 ...


head(clients)
       ClientID  Country       CountryType  OrderSize
1      58187855  United States              12.95
2      59210128  France                     21.99
3      65729284  Pakistan                   5.00
4      25819711  United States              7.50
5      62837458  United States              44.55
6      88379852  China                      99.28

The function I attempted to write is this:

updateCountry <- function(x) {
  if (clients$Country == "US") {
        clients$CountryType <- "US"
  } else {
    clients$CountryType <- "Foreign"
    }
}

I would then apply it like so:

sapply(clients, updateCountry)

When I run sapply against the head of the dataframe, I get this:

"US" "US" "US" "US" "US" "US" 
Warning messages:
1: In if (clients$Country == "United States") { :
  the condition has length > 1 and only the first element will be used
2: In if (clients$Country == "United States") { :
  the condition has length > 1 and only the first element will be used
3: In if (clients$Country == "United States") { :
  the condition has length > 1 and only the first element will be used
4: In if (clients$Country == "United States") { :
  the condition has length > 1 and only the first element will be used
5: In if (clients$Country == "United States") { :
  the condition has length > 1 and only the first element will be used
6: In if (clients$Country == "United States") { :
  the condition has length > 1 and only the first element will be used

It appears that the function is classifying the Country correctly, but is not updating the clients$CountryType column correctly. What am I doing wrong? Also – is this the best way to accomplish updating the dataframe?

Answer 1

ifelse seems like what you actually want here. It’s a vectorized version of the if/else construct.

 clients$CountryType <- ifelse(clients$Country == "US", "US", "Foreign")