[R] Summarizing factor data in table?
Andy Bunn
abunn at whrc.org
Tue Apr 26 19:28:02 CEST 2005
I have a very simple query with regard to summarizing the number of factors
present in a certain snippet of a data frame.
Given the following data frame:
foo <- data.frame(yr = c(rep(1998,4), rep(1999,4), rep(2000,2)), div =
factor(c(rep(NA,4),"A","B","C","D","A","C")),
org = factor(c(1:4,1:4,1,2)))
I want to get two new variables. Object ndiv would give the number of
divisions by year:
1998 0
1999 3
2000 2
Object norgs would give the number of organizations
1998 4
1999 4
2000 2
I figure xtabs should be able to do it, but I'm stuck without a for loop.
Any suggestions? -Andy
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