match(x, table, nomatch=NA) x %in% table
x
| the values to be matched. |
table
| the values to be matched against. |
nomatch
| the value to be returned in the case when no match is found. |
match: If x[i] is found to equal table[j]
then the value returned in the i-th position of the return value is
j. If no match is found, the value is nomatch.
%in%: A utility function, currently defined as
"%in%" <- function(x, y) match(x, y, nomatch = 0) > 0 allowing
an intuitive usage and returning a logical vector of length length(x).
pmatch and charmatch for (partial)
string matching, match.arg, etc for function argument matching.
## The intersection of two sets :
intersect <- function(x, y) y[match(x, y, nomatch = 0)]
intersect(1:10,7:20)
1:10 %in% c(1,3,5,9)
sstr <- c("c","ab","B","bba","c","@","bla","a","Ba","%")
sstr[sstr %in% c(letters,LETTERS)]
"%w/o%" <- function(x,y) x[!x %in% y] #-- x without y
(1:10) %w/o% c(3,7,12)