Hi Steven,

See the prob argument under ?quantile.  The following should be what you
want:

tapply(x, l.c.1, quantile, prob = 0.75)


HTH,
Jorge
*

*

On Thu, Mar 24, 2011 at 7:18 PM, Steven Ranney <> wrote:

> 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
>
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