[R] How to access a column by its label?

[Marc Schwartz (via MN)]

On Thu, 2006-08-03 at 14:44 -0400, Neil McLeod wrote:
> Hi all,
> 
> Is there any way to access a column of a data frame by its label (title)
> rather than its column index? For example, I'd like to be able to select
> animals[,"weight"] rather than animals[,3], if the third column of the
> "animals" data frame has the label "weight".
> 
> Thank you!

You answered your own question...animals[,"weight"]

You can also do:

animals$weight

or

animals[["weight"]]

or 

subset(animals, select = weight)


See ?Extract and ?subset for more information.

HTH,

Marc Schwartz