Use data.frame in custom function?

Question

Often functions that work with data.frames have the ability to let the user provide a dataset, so that the user can use its columns in a straight forward way. E.g.:

lm(mpg~cyl+gear,data=mtcars)

Instead of using mtcars$cyl in the formula, we can simply use cyl. How can I implement such behavior in custom built functions?

You can always look at the source of lm and see what's going on, or this wiki by Hadley may be of interest: github.com/hadley/devtools/wiki/Evaluation — Chase
– Chase, Commented Jan 12, 2012 at 15:26
very nice. thx Chase and James . Sometimes i just seem to forget about nice things... — Matt Bannert
– Matt Bannert, Commented Jan 12, 2012 at 15:41
Another good place to look for a worked example is the subset.data.frame function code. — IRTFM
– IRTFM, Commented Jan 12, 2012 at 17:28
Here was my answer to a recent ~ identical question: stackoverflow.com/questions/8484664/… — Josh O'Brien
– Josh O'Brien, Commented Jan 12, 2012 at 17:59
+1 on that other thread for you Josh, I think i am finally gettin started with other environments but global. Thx for the more elaborate answer though. — Matt Bannert
– Matt Bannert, Commented Jan 12, 2012 at 18:04

Richie Cotton · Accepted Answer · 2012-01-12 16:20:23Z

1

There are several different techniques for this, described in Standard nonstandard valuation rules.

answered Jan 12, 2012 at 16:20

Richie Cotton

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