[R] densities from a list with data.frames

Charilaos Skiadas cskiadas at gmail.com
Fri Apr 11 14:09:24 CEST 2008

Did you try Richie's suggestion? The x[,1] part will pick out the  
first column of the data frame. Seems to do exactly what you asked for.

Haris Skiadas
Department of Mathematics and Computer Science
Hanover College

On Apr 11, 2008, at 7:57 AM, Antje wrote:

> Of course, I know, but I cannot apply the function "density" to a  
> data frame
> (which is the element of the list) but to a vector coming from a  
> data frame.
> That's my problem I'd like to solve...
> Richard.Cotton at hsl.gov.uk schrieb:
>>> I have a list which consists of data frames (all data frames have  
>>> the
>> same
>>> amount and type of columns but different length).
>>> Now, I'd like to calculate for each data frame in the list the
>>> density function
>>> of the values of the fist column ($V1).
>>> This list could be an example:
>>> l <- list( data.frame(rnorm(100)), data.frame(rnorm(20)), data.
>>> frame(rnorm(200)) )
>> If you want to do the same thing to every element of a list,  
>> lapply (or
>> sapply) is your friend.
>> Try:
>> lapply(l, function(x) density(x[,1]))
>> Regards,
>> Richie.
>> Mathematical Sciences Unit
>> HSL

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