[R] Loop does not work: Error in else statement

[PIKAL Petr]

Hi

> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-
> project.org] On Behalf Of Frank S.
> Sent: Monday, September 29, 2014 9:17 PM
> To: r-help at r-project.org
> Subject: [R] Loop does not work: Error in else statement
>
> Hi to all members of R list,
>
>
>
> I m working with data.table package, and with 6
> variables: "ID" (Identifier), "born" (Birthdate), "start" (Starting
> date), "register" (date of measurement), "value"and "end" (date of
> expiration). So, the natural order of dates would be: born =< start =<
> register =< end.  As an example, I have: DT <- data.table(ID =
> as.factor(rep(1:4,each=2)),
>
>      born =
> as.Date(rep(c("1955-02-20", "1990-07-25", "1972-03-18", "1988-05-
> 03"),each=2)),
>
>      start =
> as.Date(rep(c("1953-03-28", "1990-07-01", "1983-09-05", "1988-07-
> 18"),each=2)),
>
>      register =
> as.Date(c("1955-08-11", "1958-03-28",
> "1990-07-09", "1992-07-01",
>
>                 "1983-09-05",
> "2002-09-28", "1992-07-10", "1993-03-12")),
>
>      value =
> c(205, 346, 34, 76, 320, 148, 209, 274),
>
>      end =
> as.Date(rep(c("1960-11-05", "1997-10-15", "2002-09-27", "1997-03-
> 02"),each=2)))
>
>
>
> I would want to make 3 operations:1. First: Remove entire ID s where
> "start" is previous to "born" date (excepting those subjects whose
> month and year values are the same in "start" and "born" variables: I
> assign "born"
> date to "start" date in these cases).Afterwords:2. Remove only specific
> rows (not all ID) where  register  is previous to  start .3.Remove only
> specific rows (not all ID) where  end  is previous to  register .
>
> I have: DT[ , {    if (all(born > start))       {     indx <-
> which(paste(year(born)) == paste(year(start)) &  paste(month(born)) ==
> paste(month(start)))      result <- list(born=born[indx],
> start=born[indx], register=register[indx], value=value[indx],
> end=end[indx])      }        if (all(register > start) | all(end >
> register))         {         indx <- which((register > start) | (end >
> register))         result <- list(born=born[indx], start=start[indx],
> register=register[indx], value=value[indx], end=end[indx])          }
> else         {         NULL         }   else     {     indx <-
> which(all(register > start) | all(end > register))     result <-
> list(born=born[indx], start=start[indx], register=register[indx],
> value=value[indx], end=end[indx])      }   result   }, by=ID] BUT I GET
> AN ERROR MESSAGE: Error: syntax error, unexpected ELSE in "else"
> Please, can anyone help me? Thank you!!

Missing parentheses? Missing comma? Syntactically valid expression before else?

From HTML scrambled post hard to tell.

Wild guess.

some if statement could be evaluated without before else statement as valid.

if (something) {do this}
else {do that}

results in error as first line is evaluated and else is not needed for this evaluation. Therefore you start the second line without leading if.

if (something) {do this} else
{do that}

is valid and does not throw error.

Maybe it is covered in FAQs

Regards
Petr




>
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