[R] Summary Statistics for data.frame

justin rapp jdrapp at gmail.com
Sat Jul 8 21:44:48 CEST 2006

I apologize for my constant questions but I am new to R and trying to
gain an appreciation for its capabilities.  The following task is easy
in Excel and I was hoping somebody could give me a quick explanation
for how it can be acheived in R so I can avoid having to switch
between the two applications.

How do I find the Summary Statistics in one Vector of the dataframe by
levels in another of the vectors.

For example, I have the following headings for my data.frame.
Year Drafted

I would like to see compute the mean Height, Weight, and Ratio as well
as their variances for each of the years under Year
Drafted(1980-2000).  What is the most efficient way of doing this?

Thank you.

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