[R] Passing variable names in quotes to a function

[Brant Inman]

Thank you for your response.  Here is the problem that I find with your code (which I had tried).  When you pass a value to the subset argument of the function, it will not hold the quotes on the subsetting variable’s value.

For example, if I want the function to do  Y[Z==‘skinny’] so that we use only those values of Y where Z is equal to skinny, I need to be able to retain the quotes around skinny. If you try passing “Z==“skinny”” to the  function, it will remove the quotes and give you Z==skinny, which does not work in the subsetting code.




> On Dec 2, 2015, at 7:10 AM, phgrosjean at sciviews.org wrote:
> 
> Your example and explanation are not complete, but I have the gut feeling that you could do all this both more efficiently *and* more R-ish.
> 
> First of all, why would you pass Y and X separately, to ultimately build the Y ~ X formula within the body of your function?
> 
> Secondly, it seems to me that subY and subY.val does something very similar to the subset argument in, say, lm().
> 
> Personally, I would write it like this:
> 
> foo <- function(formula, data, subset) {
>  if (!missing(subset))
>    data <- data[subset, ]
>  fit <- some_regression_tool(formula, data = data)
> 
>  ## <more code>
> 
>  data_after_processing
> }
> 
> with subset = subY == subY.val.
> 
> Best,
> 
> Philippe
> 
>> On 02 Dec 2015, at 06:11, Brant Inman <brant.inman at me.com> wrote:
>> 
>> I am trying to build a function that can accept variables for a regression.  It would work something like this:
>> 
>> ---
>> # Y = my response variable (e.g. income)
>> # X = my key predictor variable (e.g. education)
>> # subY = a subsetting variable for Y (e.g. race)
>> # subY.val = the value of the subsetting value that I want (e.g. ‘black’)
>> 
>> foo <- function(Y, X, subY, subY.val, dataset){
>> 
>> if(is.na(subY) == F) {
>>    Y <- paste(Y, ‘[‘, subY, ‘==‘, subY.val, ‘]’)
>> }
>> FORMULA <- paste(Y ~ X)
>> fit <- some.regression.tool(FORMULA, data=dataset)
>> 
>> return(some.data.after.processing)
>> }
>> ---
>> 
>> If I call this function with, foo(income, education, race, “black”, my.dataset), I do not get the result that I need because the FORMULA is "income[race==black] ~ education” when what I need is “income[race==‘black’] ~ education”.  How do I get the quotes to stay on ‘black’?  Or, is there a better way?
>> 
>> Help appreciated.
>> 
>> --
>> Brant
>> 	[[alternative HTML version deleted]]
>> 
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