frequency
Are the data in a data frame? Is it the first letter of the id that defines unique ID's or something else? Depending on your answers: ?substring ?table ?with may be useful, as in with(yourdata,table(substring(ID,1,1))) ... or not, if you meant something else. -- Bert On Tue, Oct 23, 2012 at 12:14 PM, farnoosh sheikhi
<farnoosh_81 at yahoo.com> wrote:
Hello,
I have a data as follow:
ID Visit
xa1
xa2
yb1
yc23
yb33
I want to look at frequency of visit for ID and create a new column as response .
For example my response would be 2 for x and 3 for y.
I think I need to write a loop, but I don't know how.
I really appreciate your help.
Thanks a lot.
Best,Farnoosh Sheikhi
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Bert Gunter Genentech Nonclinical Biostatistics Internal Contact Info: Phone: 467-7374 Website: http://pharmadevelopment.roche.com/index/pdb/pdb-functional-groups/pdb-biostatistics/pdb-ncb-home.htm