Best r questions in November 2011

Splitting a string on the first space

11 votes

I'd like to split a vector of character strings (people's names) into two columns (vectors). The problem is some people have a 'two word' last name. I'd like to split the first and last names into two columns. I can slit out and take the first names using the code below but the last name eludes me. (look at obs 29 in the sample set below to get an idea as the Ford has a "last name" of Pantera L that must be kept together)

What I have attempted to do so far;

x<-rownames(mtcars)
unlist(strsplit(x, " .*"))

What I'd like it to look like:

            MANUF       MAKE
27          Porsche     914-2
28          Lotus       Europa
29          Ford        Pantera L
30          Ferrari     Dino
31          Maserati    Bora
32          Volvo       142E

The regular expression rexp matches the word at the start of the string, an optional space, then the rest of the string. The parenthesis are subexpressions accessed as backreferences \\1 and \\2.

rexp <- "^(\\w+)\\s?(.*)$"
y <- data.frame(MANUF=sub(rexp,"\\1",x), MAKE=sub(rexp,"\\2",x))
tail(y)
#       MANUF      MAKE
# 27  Porsche     914-2
# 28    Lotus    Europa
# 29     Ford Pantera L
# 30  Ferrari      Dino
# 31 Maserati      Bora
# 32    Volvo      142E