Ray Ray -4 years ago 100
R Question

Source-ing an .R script within a function and passing a variable through (RODBC)

I have encountered a bit of a hiccup in something I'm working on. Suppose I have the following simple example. Let...

v <- c(606:608) ## Some vector of integers


I also, have a separate script written (let's just call it
foo.R
) which has something like (uses the
RODBC
package):

um <- sqlQuery(artemis,paste("select * from port.tdtf_VaR_Unmatched (",LatestModelRun,")",sep=""))


Now suppose I want to run the following loop function:

test <- function() {
for (i in 1:length(v)) {
LatestModelRun <- v[i]
source("C:/R/foo.r")
print(unmatched)} }

test() ## Run it


When I do this, I get the following error:
Error in paste("\n\tselect * from port.tdtf_VaR_Unmatched (", LatestModelRun, :
object 'LatestModelRun' not found


So, somehow it's not reading in the
LatestModelRun
variable defined within the
test
function.

Here's the
traceback()
:

7: paste("\n\tselect * from port.tdtf_VaR_Unmatched (", LatestModelRun,
")\n\twhere [PortfolioProduct] not in ('REC - Generic','REC - Green-e NY')\n\torder by [PortfolioProduct], [Year]",
sep = "")
6: odbcQuery(channel, query, rows_at_time)
5: sqlQuery(artemis, paste("\n\tselect * from port.tdtf_VaR_Unmatched (",
LatestModelRun, ")\n\twhere [PortfolioProduct] not in ('REC - Generic','REC - Green-e NY')\n\torder by [PortfolioProduct], [Year]",
sep = ""))
4: eval.with.vis(expr, envir, enclos)
3: eval.with.vis(ei, envir)
2: source("C:/R/foo.r")
1: test()


Anybody have an idea as to what I'm doing wrong??

Any help is much appreciated!! Thanks!!

Answer Source

As I said in my comment, the source'd code is evaluated in the global environment by default. Set local=TRUE to evaluate the code in the calling environment.

test <- function() {
  for (i in 1:length(v)) {
    LatestModelRun <- v[i]
    source("C:/R/foo.r", local=TRUE)
    print(unmatched)
  }
}
v <- c(606:608)
test()
# [1] "select * from port.tdtf_VaR_Unmatched (606)"
# [1] "select * from port.tdtf_VaR_Unmatched (607)"
# [1] "select * from port.tdtf_VaR_Unmatched (608)"

where foo.r contains:

unmatched <-
  paste("select * from port.tdtf_VaR_Unmatched (",LatestModelRun,")",sep="")
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