[R] writing function

[Joshua Wiley]

My guess is that either ls(), called inside grep() or mget() is
looking in an environment you do not want it to.  When you create a
function, it has it's own environment.  If you want the dataframes to
be created inside the function call (which is what I think you were
doing before), you should set ls() and mget() to use your function
environment.  If the dataframes are supposed to be in the global
environment, I would try adding:

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

HTH,

Josh

On Mon, May 24, 2010 at 9:17 AM, arnaud Gaboury
<arnaud.gaboury at gmail.com> wrote:
> Dear group,
>
> Here is my environment after I run a function, myfun()
>
>>myfun()
>> ls()
>  [1] "allcon"        "avprix16"      "DailyPL100416" "DailyPL100419"
> "DailyPL100420" "l"             "ll"            "myl"           "PL"
> "PLdaily"       "PLglobal"      "PLmonthly"
> [13] "Pos100415"     "Pos100416"     "Pos100419"     "Pos100420"
> "pose15"        "pose16"        "position"      "r"             "result"
> "sel"           "select"        "Trad100415"
> [25] "Trad100416"    "Trad100419"    "Trad100420"    "trade"         "tt"
> "value"         "w"             "zz"
>
> Elements "DailyPL100416" "DailyPL100419" "DailyPL100420" are data frames
> created by a function, myfun().
> If then I pass this line manually at the prompt:
>
>>dd<-data.frame(do.call(rbind,
> mget(grep("DailyPL",ls(),value=TRUE),envir=.GlobalEnv)),row.names=NULL)
>
> Here is what I get, wich is the expected result :
>
> dd <-
> structure(list(DESCRIPTION = structure(c(2L, 5L, 6L, 7L, 9L,
> 11L, 12L, 15L, 14L, 16L, 1L, 10L, 3L, 4L, 13L, 8L, 17L, 2L, 3L,
> 5L, 7L, 9L, 11L, 12L, 13L, 14L, 16L, 18L, 8L, 6L, 10L, 15L, 5L,
> 19L, 9L, 10L, 11L, 12L, 13L, 14L, 16L, 2L, 3L, 20L, 18L, 7L,
> 21L), .Label = c("COFFEE C Jul/10", "COPPER May/10", "CORN Jul/10",
> "CORN May/10", "COTTON NO.2 Jul/10", "CRUDE OIL miNY May/10",
> "GOLD Jun/10", "HENRY HUB NATURAL GAS May/10", "ROBUSTA COFFEE (10) Jul/10",
>
> "SILVER May/10", "SOYBEANS Jul/10", "SPCL HIGH GRADE ZINC USD",
> "STANDARD LEAD USD", "SUGAR NO.11 Jul/10", "SUGAR NO.11 May/10",
> "WHEAT Jul/10", "WHEAT May/10", "CRUDE OIL miNY Jun/10", "HENRY HUB NATURAL
> GAS Jun/10",
> "PALLADIUM Jun/10", "PLATINUM Jul/10"), class = "factor"), PL = c(3500,
> -1874.99999999999, -2612.50000000003, -2169.99999999998, -680,
> 425, 1025, 1008.00000000000, -3057.59999999999, 3212.5, -1781.25000000001,
> -2265.0, 75, -387.5, 2950, 490.000000000013, 0, 2612.49999999998,
> -4162.5, 279.99999999998, 589.999999999964, -3670, -1212.5, 887.5,
> -625, 3976.00000000000, -7250, -1112.50000000000, -289.999999999999,
> -1414.99999999999, 275, -526.400000000003, 6914.99999999999,
> -19.9999999999978, -2330, 54.9999999999955, 1725, -3012.5, -5175,
> -1769.60000000001, 3787.5, -537.500000000009, 175, -5330.00000000001,
> 362.49999999999, 590.000000000009, -2995.00000000000)), .Names =
> c("DESCRIPTION",
> "PL"), row.names = c(NA, -47L), class = "data.frame")
>
> If I add this same line at the end of my function , here is what I get:
>
>> myfun()
> data frame with 0 columns and 0 rows  #dd doesn't return
>
>
> What is wrong?
>
> Thank you for help.
>
> ______________________________________________
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> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>



-- 
Joshua Wiley
Senior in Psychology
University of California, Riverside
http://www.joshuawiley.com/