Thnaks for your reply,
By using tapply I get this result:
tapply(df$BR, findInterval(df$BR, quantile(df$BR)), mean)
1 3 4 5
256 320 384 512
But I think this is not true,cause I have to get 5 means but here I get four
numbers!
On Monday, May 16, 2016 6:29 AM, Michael Dewey <li...@dewey.myzen.co.uk> wrote:
Dear Elahe
In line
On 16/05/2016 13:31, ch.elahe via R-help wrote:
> Hi all,
> I have a column in my df and I want to get quartiles for this column and then
> calculate mean for each and every quartile, here is my column:
>
The quartiles are strictly speaking the boundaries but if you really
meant that the problem is trivial so i assume you want to cut the
variable at the quartiles.
>
> df$BR
> [1] 384 384 384 384 512 384 384 320 320 320 320 320 320 320 320 320 320
> 384
> [19] 384 384 320 320 320 320 384 384 256 320 320 320 384 320 320 320 384
> 384
> [37] 320 320 320 320 320 320 320 320 320 384 320 320 320 320 320 320 384
> 320
> [55] 320 320 320 320 320 320 384 512 320 320 320 320 320 320 320 384 384
> 320
> [73] 320 320 384 320 320 320 320 256 320 320 384 320 384 320 384 320 320
> 320
> [91] 384 320 320 320 320 320 320 320 320 320 320 320
>
> I do the following to get the quartiles:
>
>
> quantile(m$BR)
> 0% 25% 50% 75% 100%
> 256 320 320 368 512
>
> now how can I get mean for each quartile?
How about setting up a vector which takes the values 1, 2, 3, 4
depending on the values of BR with cutpoints defined by
quantile(BR)(using ifelse) and then using tapply?
> Thnaks for any help,
> Elahe
>
> ______________________________________________
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--
Michael
http://www.dewey.myzen.co.uk/home.html
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