subsetting a list of dataframes

Thank you all, this is exactly what I had in mind, except that I  
still have
to get my head around apply et al. Back to the books for me then!

Read the lapply( ...)  call as:

"For every element in the object named `data`, send that element to a  
function that returns TRUE if its first dimension is greater than one,  
returns FALSE if its first dimension is one, and return nothing  
(actually a vector with zero elements) if it doesn't have a (first)  
"dim" attribute, and finally return the ordered collection of those  
values as a list which is assigned the name 'entries.with.nrows'. "
Lara

On Tue, May 17, 2011 at 2:41 PM, Jannis <bt_jannis at yahoo.de> wrote:

Have a look at lapply(). Something like:

entries.with.nrows=lapply(data,function(x)dim(x)[1]>1)

should give you a vector with the elements of the list that you  
seek marked
with TRUE.

This vector can then be used to extract a subset from your list by:

data.reduced=data[entries.with.nrows]

Or similar....

HTH
Jannis

--- Lara Poplarski <larapoplarski at gmail.com> schrieb am Di,  
17.5.2011:

Von: Lara Poplarski <larapoplarski at gmail.com>
Betreff: [R] subsetting a list of dataframes
An: r-help at r-project.org
Datum: Dienstag, 17. Mai, 2011 20:24 Uhr
Hello All,

I have a list of dataframes, and I need to subset it by
keeping only those
dataframes in the list that meet a certain criterion.
Specifically, I need
to generate a second list which only includes those
dataframes whose number
of rows is > 1.

Could someone suggest how to do this? I have come close to
what I need with
loops and such, but there must be a less clumsy way...

Many thanks,
Lara

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subsetting a list of dataframes

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