The important thing to understand is that $ is a shortcut for [[ and you
are moving into the realm where a shortcut is the longest distance between
2 points (see fortune(312)).
So your code can be something like:
state <- 'oldstate'
balance <- 'oldbalance'
dataa[[balance]][ dataa[[state]]=='AR' ]
You may also benefit from learning to use tools like "with" and "subset"
(though subset has its own complications when used inside of other
functions) or "grep" and "match" to find the columns of interest.
On Fri, Jan 18, 2013 at 12:40 PM, Yuan, Rebecca <
rebecca.yuan@bankofamerica.com> wrote:
> Hello all,
>
> I have a data frame dataa:
>
> newdate newstate newid newbalance newaccounts
> 1 31DEC2001 AR 1 1170 61
> 2 31DEC2001 VA 2 4565 54
> 3 31DEC2001 WA 3 2726 35
> 4 31DEC2001 AR 3 2700 35
>
> The following gives me the balance of state AR:
>
> dataa$newbalance[data$newstate == 'AR']
> 1170
> 2700
>
> Now, I have another different data frame datab, it is very similar to
> data, except that the name of the columns are different, and the order of
> the columns are different:
>
> oldstate olddate oldbalance oldid oldaccounts
> 1 AR 31DEC2012 1234 7 40
> 2 WA 31DEC2012 2222 3 30
> 3 VA 31DEC2012 2345 5 23
> 3 AR 31DEC2012 5673 5 23
>
> datab$oldbalance[datab$oldstate== 'AR' ]
> 1234
> 5673
>
> Could I have a way to quote
>
> data$balance[data$state == 'AR']
>
> in general, where balance=oldbalance, state=oldstate when data=dataa, and
> balance = newbalance, state = newstate when data=datab ?
>
> Thanks very much!
>
> Cheers,
>
> Rebecca
>
> ----------------------------------------------------------------------
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