On Jul 2, 2009, at 9:13 AM, Neil Tiffin wrote:
As an R beginner, I feel brain dead today as I can not find the
answer to a relatively simple question.
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?
Neil
Try this:
subset(data_frame, name %in% c("sue", "jane"), select = c(name,
age, birthdate))
or if your vector of names is:
Names <- c("mary", "bob", "danny", "sue", "jane")
subset(data_frame, name %in% Names, select = c(name, age, birthdate))
See ?"%in%" for more information.
HTH,
Marc Schwartz
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