Message-ID: <4D9CD1A5.1070503@gmail.com>
Date: 2011-04-06T20:48:37Z
From: Duncan Murdoch
Subject: Need a more efficient way to implement this type of logic in R
In-Reply-To: <4D9CC6D5.9060709@gmail.com>
On 06/04/2011 4:02 PM, Walter Anderson wrote:
> I have cobbled together the following logic. It works but is very
> slow. I'm sure that there must be a better r-specific way to implement
> this kind of thing, but have been unable to find/understand one. Any
> help would be appreciated.
>
> hh.sub<- households[c("HOUSEID","HHFAMINC")]
> for (indx in 1:length(hh.sub$HOUSEID)) {
> if ((hh.sub$HHFAMINC[indx] == '01') | (hh.sub$HHFAMINC[indx] == '02')
> | (hh.sub$HHFAMINC[indx] == '03') | (hh.sub$HHFAMINC[indx] == '04') |
> (hh.sub$HHFAMINC[indx] == '05'))
> hh.sub$CS_FAMINC[indx]<- 1 # Less than $25,000
The answer is to think in terms of vectors and logical indexing. The
code above is equivalent to
hh.sub$CS_FAMINC[ hh.sub$HHFAMINC %in% c('01', '02', '03', '04', '05') ]
<- 1
I've left off the rest of the loop, but I think it's similar.
Duncan Murdoch