Re: [R] subsetting a list of dataframes

2011-05-18 Thread William Dunlap
> -Original Message- > From: r-help-boun...@r-project.org > [mailto:r-help-boun...@r-project.org] On Behalf Of Lara Poplarski > Sent: Tuesday, May 17, 2011 4:14 PM > To: r-help@r-project.org > Subject: Re: [R] subsetting a list of dataframes > > Thank you all, th

Re: [R] subsetting a list of dataframes

2011-05-18 Thread David Winsemius
On May 17, 2011, at 7:13 PM, Lara Poplarski wrote: 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

Re: [R] subsetting a list of dataframes

2011-05-17 Thread Lara Poplarski
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! Lara On Tue, May 17, 2011 at 2:41 PM, Jannis wrote: > Have a look at lapply(). Something like: > > entries.with.nrows=lapply(data,function(x)dim(x)[1]>1)

Re: [R] subsetting a list of dataframes

2011-05-17 Thread Jannis
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 s

Re: [R] subsetting a list of dataframes

2011-05-17 Thread Rolf Turner
On 18/05/11 08:24, Lara Poplarski wrote: 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. C

Re: [R] subsetting a list of dataframes

2011-05-17 Thread William Dunlap
shouldKeep <- sapply(listOfDataFrames, function(df)nrow(df)>1) listOfDataFrames[shouldKeep] or, compressed to get rid of the intermediate variable listOfDataFrames[sapply(listOfDataFrames, function(df)nrow(df)>1)] If you are writing production code and there is any chance that listOfDataFra

Re: [R] subsetting a list of dataframes

2011-05-17 Thread Jorge Ivan Velez
Hi Lara, You might try the following (untested): yourlistofdataframes[sapply(yourlistofdataframes, function(d) nrow(d) > 1)] HTH, Jorge On Tue, May 17, 2011 at 4:24 PM, Lara Poplarski <> wrote: > Hello All, > > I have a list of dataframes, and I need to subset it by keeping only those > dataf