[R] Multiple line commands in R scripting

Peter Ehlers ehlers at ucalgary.ca
Sun Oct 25 19:41:57 CET 2009


As usual, you're Duncan. Should have tested it. Thanks for the correction.

  -Peter Ehlers

Duncan Murdoch wrote:
> On 25/10/2009 11:43 AM, Peter Ehlers wrote:
>> Here are two ways:
>>
>> 1. wrap the line in braces:
>>
>>   x <- {....
>>         /...}
> 
> That doesn't work.  You're probably thinking of the way the parsing of 
> if versus if/else depends on braces:
> 
>  if (TRUE) print("TRUE")
>  else print("FALSE")
> 
> is a syntax error, except when wrapped in braces.
> 
> Duncan Murdoch
> 
>>
>> 2. maybe more awkward in general, but sometimes useful:
>>
>>   x <- `/`(... ,
>>         ...)
>>
>>   -Peter Ehlers
>>
>> 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.
>>>
>>> Thank you,
>>> Neil.
>>>
>>> ______________________________________________
>>> R-help at r-project.org mailing list
>>> https://stat.ethz.ch/mailman/listinfo/r-help
>>> PLEASE do read the posting guide 
>>> http://www.R-project.org/posting-guide.html
>>> and provide commented, minimal, self-contained, reproducible code.
>>>
>>>
>>
>> ______________________________________________
>> R-help at r-project.org mailing list
>> https://stat.ethz.ch/mailman/listinfo/r-help
>> PLEASE do read the posting guide 
>> http://www.R-project.org/posting-guide.html
>> and provide commented, minimal, self-contained, reproducible code.
> 
>




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