Hi Eric,
Try
# data
x <- structure(list(House_number = 1:4, Inspected = structure(c(3L,
4L, 1L, 2L), .Label = c("10/31/2011", "8/3/2011", "9/2/2011",
"9/4/2011"), class = "factor"), Sold = structure(c(1L, 2L, 4L,
3L), .Label = c("10/10/2011", "10/20/2011", "11/1/2011", "8/28/2011"
), class = "factor")), .Names = c("House_number", "Inspected",
"Sold"), class = "data.frame", row.names = c(NA, -4L))
> with(x, as.Date(Inspected, "%m/%d/%y") - as.Date(Sold, "%m/%d/%y") > 0)
[1] FALSE FALSE TRUE FALSE
> x[with(x, as.Date(Inspected, "%m/%d/%y") - as.Date(Sold, "%m/%d/%y") >
0), ]
House_number Inspected Sold
3 3 10/31/2011 8/28/2011
See ?as.Date for more information.
HTH,
Jorge.-
On Mon, 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")
>
> But that busted. I've bent over backward to make these kinds of comparisons
> work, but there has to be a better way. Any help would be most welcome.
>
> Thanks,
>
> Eric
>
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>
> ______________________________________________
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>
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