On Feb 10, 2010, at 5:58 PM, travelmail wrote:
Hello,
I have an education dataset and I'd like to know how to count the
number of
courses each student has taken in a particular subject. For
instance, say
the course codes for "History" are 20-26 & 31 and I have the
following data
Student ID Course Code
1 16
1 17
1 21
1 31
2 10
2 22
2 23
2 24
I would like a separate variable that reads like this
Student ID Hist Courses
1 2
2 3
> table( courses[courses$CourseCode %in% c(20:26, 31), ]$StudentID)
1 2
2 3
> data.frame( ctab)
Var1 Freq
1 1 2
2 2 3
You can rename as you desire but please try to stop using spaces. Very
unReliable.
I've read other "count" tutorials on the forum, but couldn't still
find an
answer to my problem. Thanks for helping out!
Greg
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