[R] Your personal email on the R-help mail list

[David L Carlson]

Yes. I thought I was replying to a different message. Sorry.

David

-----Original Message-----
From: Chel Hee Lee [mailto:chl948 at mail.usask.ca] 
Sent: Thursday, January 29, 2015 11:33 AM
To: David L Carlson
Subject: Your personal email on the R-help mail list

Hi David,

I am not sure if you noticed that your personal conversation is on the 
R-help mailing list.

Chel Hee Lee, PhD

Biostatistician and Manager
Clinical Research Support Unit
College of Medicine
University of Saskatchewan
Canada

On 1/29/2015 11:28 AM, David L Carlson wrote:
> That's fine, but I'm here in town if you want me to pick her up at the airport.
>
> David
>
> -----Original Message-----
> From: R-help [mailto:r-help-bounces at r-project.org] On Behalf Of Chel Hee Lee
> Sent: Thursday, January 29, 2015 9:18 AM
> To: Jeff Newmiller; Alan Yong; r-help at r-project.org
> Subject: Re: [R] Passing a Data Frame Name as a Variable in a Function
>
> I like Jeff's comments on the previous post.
>
> Regarding Alan's question, please see the following example.
>
>   > df.1 <- data.frame(v1=1:5, v2=letters[1:5])
>   > df.2 <- data.frame(v1=LETTERS[1:3], v2=11:13)
>   > DFName <- ls(pattern = glob2rx("df.*"))[1]
>   > DFName
> [1] "df.1"
>   > length(DFName[,1])
> Error in DFName[, 1] : incorrect number of dimensions
>
> 'DFName' is a character vector of length 1 (it is neither a matrix nor a
> data frame).  In this case, you may try 'eval()' as below:
>
>   > eval(parse(text=DFName))
>     v1 v2
> 1  1  a
> 2  2  b
> 3  3  c
> 4  4  d
> 5  5  e
>   > eval(parse(text=DFName))[,1]
> [1] 1 2 3 4 5
>   > length(eval(parse(text=DFName))[,1])
> [1] 5
>   >
>
> Is this what you are looking for?  I hope this helps.
>
> Chel Hee Lee
>
>
> On 1/29/2015 12:34 AM, Jeff Newmiller wrote:
>> This approach is fraught with dangers.
>>
>> I recommend that you put all of those data frames into a list and have your function accept the list and the name and use the list indexing operator mylist[[DFName]] to refer to it. Having functions that go fishing around in the global environment will be hard to maintain at best, and buggy at worst.
>>
>> That said, I usually work with all of my data frames combined as one and use the plyr, dplyr, or data.table packages to apply my algorithms to each group of rows identified by a character or factor column.
>> ---------------------------------------------------------------------------
>> Jeff Newmiller                        The     .....       .....  Go Live...
>> DCN:<jdnewmil at dcn.davis.ca.us>        Basics: ##.#.       ##.#.  Live Go...
>>                                         Live:   OO#.. Dead: OO#..  Playing
>> Research Engineer (Solar/Batteries            O.O#.       #.O#.  with
>> /Software/Embedded Controllers)               .OO#.       .OO#.  rocks...1k
>> ---------------------------------------------------------------------------
>> Sent from my phone. Please excuse my brevity.
>>
>> On January 28, 2015 5:37:34 PM PST, Alan Yong <alanyong at caltech.edu> wrote:
>>> Dear R-help,
>>> I have df.1001 as a data frame with rows & columns of values.
>>>
>>> I also have other data frames named similarly, i.e., df.*.
>>>
>>> I used DFName from:
>>>
>>> DFName <- ls(pattern = glob2rx("df.*"))[1]
>>>
>>> & would like to pass on DFName to another function, like:
>>>
>>> length(DFName[, 1])
>>>
>>> however, when I run:
>>>
>>>> length(DFName[, 1])
>>> Error in DFName[, 1] : incorrect number of dimensions
>>>
>>> and
>>>
>>> length(df.1001[, 1])
>>> [1] 104
>>>
>>> do not provide the same expected answer.
>>>
>>> How can I successfully pass the data frame name of df.1001 as a
>>> variable named DFName in a function?
>>>
>>> Thanks,
>>> Alan
>>>
>>> ______________________________________________
>>> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
>>> 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 -- To UNSUBSCRIBE and more, see
>> 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 -- To UNSUBSCRIBE and more, see
> 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.
>