R help - Jun 2007 - Use of the "by" command for gini()

I have a data set that contains income data and a group identifier. Sort of
like:


       DATA

Group,Income
A,2300
B,6776
A,6668
A,6768
B,9879
C,5577
A,7867
(etc),(etc)

I am trying to compute the gini coefficient for each group.

I have tried the following and none seem to do the trick:

1)

attach(DATA)

by(DATA, group, function(x) gini(income))


2)

attach(data)

tapply(income, group, function(x) gini(income))

Both of these return the same value for all groups. Like:

group: A
[1] 0.2422496
------------------------------------------------------------
group: B
[1] 0.2422496
------------------------------------------------------------
group: C
[1] 0.2422496
------------------------------------------------------------
group: D
[1] 0.2422496

Any ideas on how I can make this work? I need the fastest way since I am
gonna run a monte carlo based on this routine once I get the basics working.

Thanks,

EG

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