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
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