[R] When customizing last line, the code stops working

[Duncan Murdoch]

On 03/11/2016 8:29 AM, Frank S. wrote:
> Dear all,
>
>
> The function I present works perfectly when I run it as written (that is, leaving NEW LINE as commented). However, when
>
> I try to run the same function via this mentioned line (and therefore commenting LAST LINE) R gives an error message:
> Error in FUN(X[[i]], ...) : object 'dt_sp_1' not found. I do not understand why I don't get the same result.

You aren't specifying the "envir" argument to "get", so it defaults to 
the environment from which you called get, and that's the evaluation 
frame of lapply() (or maybe of do.call()).

Write the last line as

union <- do.call(rbind, lapply(paste0("dt_sp_", 1:length(sp)), get, envir = environment()))


and it works.

Duncan Murdoch
>
>
> Thanks in advance for any help!
>
>
> Frank S.
>
>
> all.sp <- function(age.u, open, close) {
>
> require(data.table)
> dt <- data.table( id = c(rep(1, 2), 2:4, rep(5, 2)),
>     sex = as.factor(rep(c(0, 1), c(3, 4))),
>     fborn =  as.Date(c("1935-07-25", "1935-07-25", "1939-07-23", "1943-10-05",
>                        "1944-01-01", "1944-09-07", "1944-09-07")) )
>
> sp <- seq(open, close, by = "year")
> dt_sp <- list()
> for (i in 1:length(sp)) {
>    vp <- as.POSIXlt(c(as.Date("1000-01-01"), sp))
>    vp$year <- vp$year - age.u
>    dt.cut <- as.numeric(cut(x = as.POSIXlt(dt$fborn), breaks = vp, right = TRUE, include.lowest = TRUE))
>    dt_sp[i] <- split(dt, factor(dt.cut, i))
>    dt_sp[[i]] <- data.table(dt_sp[[i]])[, entry_sp := sp[i]]
>    assign(paste0("dt_sp_", 1:length(sp))[i], dt_sp[[i]])
>    }
>
>    union <- rbind(dt_sp_1, dt_sp_2, dt_sp_3, dt_sp_4)     # LAST LINE: IT WORKS
>
>
>    # I TRY TO CUSTOMIZE LAST LINE, BUT THEN CODE STOPS WORKING
>    # union <- do.call(rbind, lapply(paste0("dt_sp_", 1:length(sp)), get))     # NEW LINE
> }
>
> # Example:
> result <- all.sp(age.u = 65, open = as.Date("2007-01-01"), close = as.Date("2010-05-01"))
>
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>
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