[R] extracting data from a dataframe

Marc Schwartz mschwartz at medanalytics.com
Fri Aug 2 19:08:21 CEST 2002

> -----Original Message-----
> Hi everyone,
> Here's a question about extracting data from a dataframe:
> Let's say I've got a dataframe with two vectors, TEST and GENDER.
> contains a 1 for males and 2 for females. I want to separate the
> of TEST by GENDER so I can compare their means.
> What's the most efficient way to do this with R?
> -Tim

Presuming that you wish to perform a two-sample t-test on the means, you
don't need to actually "split" the dataframe. You could use the formula
method for t.test() by the following:

t.test(df$TEST ~ df$GENDER)

where df is the name of your dataframe.

If you actually want to split the dataframe, see ?split.



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