Message-ID: <6AF7F93D-A51C-42F1-935A-6028B1E9B174@comcast.net>
Date: 2011-12-27T03:20:30Z
From: David Winsemius
Subject: comparing fields within a record
In-Reply-To: <CAGoKJb=n=-eo1fLu87pLLcpv5Ugq3N+Pj93ShW-RSnU_cyqWow@mail.gmail.com>
On Dec 26, 2011, at 7:52 PM, Eric Wolff wrote:
> Hi,
>
> I hope this isn't a really simple question, I've been struggling
> with it
> for a while.
>
> I'm looking for a way to get a function to go through a data frame
> line by
> line, compare fields, and produce a result, kind of a transform and
> an if
> statement combined (I tried to put them together and it didn't work).
>
> So, consider data Sales:
>
> House number Inspected Sold
> 1 9/2/2011 10/10/2011
> 2 9/4/2011 10/20/2011
> 3 10/31/2011 8/28/2011
> 4 8/3/2011 11/1/2011
>
> I want to find all the records which were inspected after they were
> sold.
> Ideally, this code would create a fourth field that would be a
> logical.
>
> I tried
>
> Sales<-transform(Sales, Checked=if(Sales$Inspected <= Sales$Sold)
> "OK")
dat <- within(x, Checked <- as.Date(Inspected, format="%m/%d/%Y") <
as.Date(Sold, format="%m/%d/%Y"))
Note: it might have been easier if you had converted those string or
factor variables into R Date variables.
--
David Winsemius, MD
West Hartford, CT