On 2 July 2009 at 09:13, Neil Tiffin wrote: | Given a array of string values, for example lets say "mary", "bob", | "danny", "sue", and "jane". | | I am trying to determine how to perform a logical test to determine if | a variable is an exact match for one of the string values in the array | when the number of strings in the array is variable and without using | a for loop and without comparing each value. Considering the power of | R, I thought this would be easy, but its not obvious to me. | | Now I may not yet be one with the R fu so a bit more context. | | I have a data frame that contains a column with text values. What I am | trying to do is use the subset function on the data frame to select | only data for "sue" or "jane" (for example.) But maybe I have not | taken the correct approach? | | So obviously I could do something like the following. | | subset( data_frame, name = "sue" | name == "jane", select = c(name, | age, birthdate)) | | However, my subset needs to be much more than 2 and being lazy I do | not want to type "| name == "some text" for each one. | | Is there an other way?
Yup, e.g. using the %in% operator: > set.seed(42) # fix rng so that you get the same data.frame > neil <- data.frame(rownb=1:20, name=sample(c("mary", "bob", "danny", "sue", > "jane"), 20, replace=TRUE)) > head(neil) # quick sanity check rownb name 1 1 jane 2 2 jane 3 3 bob 4 4 jane 5 5 sue 6 6 danny > neil[ neil$name %in% c("sue", "jane"), ] rownb name 1 1 jane 2 2 jane 4 4 jane 5 5 sue 7 7 sue 9 9 sue 10 10 sue 12 12 sue 13 13 jane 16 16 jane 17 17 jane > Cheers, Dirk -- Three out of two people have difficulties with fractions. ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.