replacing certain values in a data frame.

["Khan, Sohail" <khan@cshl.edu>]

Dear List,

Sorry for asking such a fundamental question.
I have really large data frame with 3 columns, I want to replace all Y's in 
column 2 with 24 and all X's with 23, then sort on column 3.  Column 3 is a 
numeric column, I want to sort in ascending order.

Thanks for any suggestions/advice.

Sohail Khan
Scientific Programmer
COLD SPRING HARBOR LABORATORY
Genome Research Center
500 Sunnyside Boulevard
Woodbury, NY 11797
(516)422-4076