[R] Multiple line commands in R scripting
David Winsemius
dwinsemius at comcast.net
Sun Oct 25 14:19:07 CET 2009
On Oct 25, 2009, at 8:53 AM, Neil Stewart wrote:
> I'm wondering whether there is a character to let R know to expect
> more
> input for a command on subsequent lines. Here is an example:
>
> test_1.R:
> x <- c(1,2,3,4)
> / c(1,2,3,4)
> x
>
> R CMD BATCh test_1.R produces test_1.Rout:
>> x <- c(1,2,3,4)
>> / c(1,2,3,4)
> Error: unexpected '/' in " /"
> Execution halted
>
>
> test_2.R:
> x <- c(1,2,3,4) /
> c(1,2,3,4)
> x
>
> R CMD BATCh test_1.R produces test_2.Rout:
>> x <- c(1,2,3,4) /
> + c(1,2,3,4)
>> x
> [1] 1 1 1 1
>
> test_2.R works as expected but test_1.R fails because the "/"
> operator is at
> the start of line 2 not the end of line 1.
>
> Is the some kind of continuation charater one can include in a
> script so R
> is expecting input on the next line? For example, in other
> languages, "\"
> works. Without this, one is forced to break lines carefully in the
> middle of
> a function, for example, to ensure R is expecting more. Any comments
> very
> welcome.
R waits for a complete command. Leave the "/" at the end of the first
line and it will then be incomplete. It is also common to see ","'s
(commas) at the end of lines in scripts.
test_1.R:
x <- c(1,2,3,4)/
c(1,2,3,4)
x
# Should "work"
> Thank you,
> Neil.
>
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> and provide commented, minimal, self-contained, reproducible code.
David Winsemius, MD
Heritage Laboratories
West Hartford, CT
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