[R] Removing objects from a list based on nrow

[Linlin Yan]

Thank Jim! You are right. I didn't notice the case of none of rows
match the condition.

On Sun, Nov 29, 2009 at 10:10 PM, jim holtman <jholtman at gmail.com> wrote:
> One thing to be careful of is if no dataframe have less than 3 rows:
>
>> df1<-data.frame(letter=c("A","B","C","D","E"),number=c(1,2,3,4,5))
>> df2<-data.frame(letter=c("A","B"),number=c(1,2))
>> df3<-data.frame(letter=c("A","B","C","D","E"),number=c(1,2,3,4,5))
>> df4<-data.frame(letter=c("A","B","C","D","E"),number=c(1,2,3,4,5))
>>
>> lst<-list(df1,df3,df4)
>> lst
> [[1]]
>  letter number
> 1      A      1
> 2      B      2
> 3      C      3
> 4      D      4
> 5      E      5
>
> [[2]]
>  letter number
> 1      A      1
> 2      B      2
> 3      C      3
> 4      D      4
> 5      E      5
>
> [[3]]
>  letter number
> 1      A      1
> 2      B      2
> 3      C      3
> 4      D      4
> 5      E      5
>
>> lst[-which(sapply(lst, nrow) < 3)]
> list()
>>
>
> Notice the list is now empty.  Instead use:
>
>> lst[sapply(lst, nrow) >=3]
> [[1]]
>  letter number
> 1      A      1
> 2      B      2
> 3      C      3
> 4      D      4
> 5      E      5
>
> [[2]]
>  letter number
> 1      A      1
> 2      B      2
> 3      C      3
> 4      D      4
> 5      E      5
>
> [[3]]
>  letter number
> 1      A      1
> 2      B      2
> 3      C      3
> 4      D      4
> 5      E      5
>
>
> On Sun, Nov 29, 2009 at 3:43 AM, Linlin Yan <yanlinlin82 at gmail.com> wrote:
>> Try these:
>> sapply(lst, nrow) # get row numbers
>> which(sapply(lst, nrow) < 3) # get the index of rows which has less than 3 rows
>> lst <- lst[-which(sapply(lst, nrow) < 3)] # remove the rows from the list
>>
>> On Sun, Nov 29, 2009 at 4:36 PM, Tim Clark <mudiver1200 at yahoo.com> wrote:
>>> Dear List,
>>>
>>> I have a list containing data frames of various numbers of rows.  I need to remove any data frame that has less than 3 rows.  For example:
>>>
>>> df1<-data.frame(letter=c("A","B","C","D","E"),number=c(1,2,3,4,5))
>>> df2<-data.frame(letter=c("A","B"),number=c(1,2))
>>> df3<-data.frame(letter=c("A","B","C","D","E"),number=c(1,2,3,4,5))
>>> df4<-data.frame(letter=c("A","B","C","D","E"),number=c(1,2,3,4,5))
>>>
>>> lst<-list(df1,df2,df3,df4)
>>>
>>> How can I determine that the second object (df2) has less than 3 rows and remove it from the list?
>>>
>>> Thanks!
>>>
>>> Tim
>>>
>>>
>>>
>>>
>>> Tim Clark
>>> Department of Zoology
>>> University of Hawaii
>>>
>>> ______________________________________________
>>> 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.
>>>
>>
>> ______________________________________________
>> 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.
>>
>
>
>
> --
> Jim Holtman
> Cincinnati, OH
> +1 513 646 9390
>
> What is the problem that you are trying to solve?
>