[R] Create macro_var in R

[ruipbarradas at sapo.pt]

Hello,

You can't use tab$MVAR but you can use tab[[MVAR]] if you do MVAR <-  
"population" (no need for c()).

Hope this helps,

Rui Barradas
 

Citando Amoy Yang via R-help <r-help at r-project.org>:

> population is the field-name in data-file (say, tab).  
> MVAR<-population takes data (in the column of population) rather  
> than field-name as done in SAS:  %let MVAR=population;
> In the following r-program, for instance, I cannot use ...  
> tab$MVAR...or simply MVAR itself since MVAR is defined as  
> "population" with double quotes if using MVAR<-c("population")
>
>    On Wednesday, February 3, 2016 11:54 AM, Duncan Murdoch  
> <murdoch.duncan at gmail.com> wrote:
>
> On 03/02/2016 12:41 PM, Amoy Yang via R-help wrote:
>>   There is a %LET statement in SAS: %let MVAR=population; Thus,  
>> MVAR can be used through entire program.
>> In R, I tried MAVR<-c("population"). The problem is that MAVR comes  
>> with double quote "...." that I don't need. But MVAR<-c(population)  
>> did NOT work out. Any way that double quote can be removed as done  
>> in SAS when creating macro_var?
>> Thanks in advance for helps!
>
> R doesn't have a macro language, and you usually don't need one.
>
> If you are only reading the value of population, then
>
> MAVR <- population
>
> is fine.  This is sometimes the same as c(population), but in general
> it's different:  c() will remove some attributes, such as
> the dimensions on arrays.
>
> If you need to modify it in your program, it's likely more complicated. 
> The normal way to go would be to put your code in a function, and have
> it return the modified version.  For example,
>
> population <- doModifications(population)
>
> where doModifications is a function with a definition like
>
> doModifications <- function(MAVR) {
>     # do all your calculations on MAVR
>     # then return it at the end using
>     MAVR
> }
>
> Duncan Murdoch
>
>         [[alternative HTML version deleted]]
>
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