[R] writing function:loop and rbind

[Joshua Wiley]

On Mon, May 24, 2010 at 7:00 AM, arnaud Gaboury
<arnaud.gaboury at gmail.com> wrote:
> One solution is to create a list, then do.call.
> Here is my environment:
>
>> ls()
>  [1] "DailyPL100416" "DailyPL100419" "DailyPL100420" "l"             "ll"
> "PLglobal"      "Pos100415"     "Pos100416"     "Pos100419"     "Pos100420"
> "position"      "r"
> [13] "result"        "sel"           "select"        "Trad100415"
> "Trad100416"    "Trad100419"    "Trad100420"    "trade"         "tt"
> "w"
>
>>   l<-list(grep("DailyPL",ls(),value=T))   #create a list of elements with
> DailyPL in the name
A list of their names, not the elements themselves.
>
>> l
> [[1]]
> [1] "DailyPL100416" "DailyPL100419" "DailyPL100420"
>
>> DF<-do.call("rbind",l)
>> DF
>     [,1]            [,2]            [,3]
> [1,] "DailyPL100416" "DailyPL100419" "DailyPL100420"
>
> That's not what I want! I expect "DF" to be a data.frame binded by row.
It is binded by row, but it is from the list you fed it, which is just
a list with a single element of character strings.
>
> I suspect there is an issue with get() or assign(), or something like that.
>
> Any help is appreciated.

I am sure there is a neater solution, but something like this should
work where envir=whether the objects actually are.

do.call(rbind, mget(grep("DailyPL",ls(),value=TRUE),envir=.GlobalEnv))

Best regards,

Josh

>
>> -----Original Message-----
>> From: arnaud Gaboury [mailto:arnaud.gaboury at gmail.com]
>> Sent: Monday, May 24, 2010 2:55 PM
>> To: r-help at r-project.org
>> Cc: 'arnaud Gaboury'
>> Subject: writing function:loop and rbind
>>
>> Dear group,
>>
>> I have a function, let's call it myfun, wich give me a list of result:
>> R1,R2,R3...
>> There is a loop in this function to get my results. Here is the
>> structure of
>> my function:
>>
>> Myfun<-function()
>>
>> {
>> For (i in X ){
>>
>> -----------instructions---------
>>
>> Ri
>>
>> {
>> {
>>
>> All Results (R1,R2...) are Data.frame. As a final result (call it
>> "Final"),
>> I need to rbind all these dataframe. One solution could be to create
>> another
>> loop, but I think I can avoid it. How can I add a line like this :
>> Final<-rbind(R1,R2...) using the i parameter? Another solution could
>> may be
>> to create a list of all my results, then apply rbind to the list?
>>
>> Any idea would be appreciated.
>>
>> TY in advance
>
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-- 
Joshua Wiley
Senior in Psychology
University of California, Riverside
http://www.joshuawiley.com/