R help - Jan 2012 - how to select column wich median is in this interval [5;6]

Hello, 
I have got a data frame df like this :
> df
   e1 e2 e3 e4
1   1 11  1 21
2   2 12  2 22
3   3 13  3 23
4   4 14  4 24
5   5 15  5 25
6   6 16  6 26
7   7 17  7 27
8   8 18  8 28
9   9 19  9 29
10 10 20 10 30

where e1 ... e3 are vectors
I have to select columns which median is in the interval [5;6] ( Here, for
instance, e1 and e3)
I would not want to use loop... (for, while)

I search for smthing like this : 
e_candidates = df[, ]
But I do not know how to write the condition, 

Thanks for your help

Thanks for your help
I'd like to know how to select 

--
View this message in context:
http://r.789695.n4.nabble.com/how-to-select-column-wich-median-is-in-this-interval-5-6-tp4290745p4290745.html
Sent from the R help mailing list archive at Nabble.com.

Not sure it's doable entirely without a for-loop, but I'd suggest
something like

df[which( (sapply(df, median) < 6) & (sapply(df, median) > 5))]

If your data frame has an enormous amount of rows, perhaps calculate
the sapply() call independently and reference the result twice.

You can probably do this without the which() call here but I'm doing
it defensively to avoid any unexpected behaviors for NAs. Finally,
note that I'm leaving out the comma in the [,] call -- it happens to
work for data frames here (and it's a good exercise to try to figure
out why) but if you want to put it back in, that won't cause problems.

Michael

On Thu, Jan 12, 2012 at 5:42 PM, ikuzar <razuki at hotmail.fr>
wrote:
> Hello,
> I have got a data frame df like this :
>> df
> ? e1 e2 e3 e4
> 1 ? 1 11 ?1 21
> 2 ? 2 12 ?2 22
> 3 ? 3 13 ?3 23
> 4 ? 4 14 ?4 24
> 5 ? 5 15 ?5 25
> 6 ? 6 16 ?6 26
> 7 ? 7 17 ?7 27
> 8 ? 8 18 ?8 28
> 9 ? 9 19 ?9 29
> 10 10 20 10 30
>
> where e1 ... e3 are vectors
> I have to select columns which median is in the interval [5;6] ( Here, for
> instance, e1 and e3)
> I would not want to use loop... (for, while)
>
> I search for smthing like this :
> e_candidates = df[, ]
> But I do not know how to write the condition,
>
> Thanks for your help
>
> Thanks for your help
> I'd like to know how to select
>
> --
> View this message in context:
http://r.789695.n4.nabble.com/how-to-select-column-wich-median-is-in-this-interval-5-6-tp4290745p4290745.html
> Sent from the R help mailing list archive at Nabble.com.
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.