[R] simple if question

[Sebastián Daza]

Hi everyone,
I have just got different samples from a dataframe (independent and 
exclusive, there aren't common elements among them). I want to create a 
variable that indicate the sampling selection of the elements in the 
original dataframe (for example, 0 = no selected, 1= sample 1, 2=sample 
2, etc.).

I have tried to do it with ifelse command, but the problem is that the 
second line replaces the values of the first line, and I haven't been 
able to do it with the if command (I got this error: In if (data$school 
%in% sample1) { :
   the condition has length > 1 and only the first element will be used)

data$selection <- ifelse(data$school %in% sample1, 1, 0)
data$selection <- ifelse(data$school %in% sample2, 2, 0)

Any ideas?
Thank you in advance.

-- 
Sebastián Daza
sebastian.daza at gmail.com