[R] tapply with specific quantile value

[Steven Ranney]

All -

I have an example data frame

x	l.c.1
43.38812035	085
47.55710661	085
47.55710661	085
51.99211429	085
51.99211429	095
54.78449958	095
54.78449958	095
56.70201864	095
56.70201864	105
59.66361903	105
61.69573564	105
61.69573564	105
63.77469479	115
64.83191994	115
64.83191994	115
66.98222118	115
66.98222118	125
66.98222118	125
66.98222118	125
66.98222118	125

and I'd like to get the 3rd quantile by l.c.1 so I use

tapply(x, l.c.1, quantile)

and my output includes all quantiles (i.e., 0, 25%, 50%, 75%, 100%)
but I'm only interested in the 75% quantile.  Is there an additional
statement or function I can use to get just the quantile that I want?

Thanks for your help -

SR
Steven H. Ranney