Hi Mark,
X = 1

assings the number 1 to X whereas

X == 1

test if X is equal to 1. I suspect you want to do this :-)   Here is an
example:

# R code
X = 1
X
# [1] 1

X == 1
# [1] TRUE


HTH,

Jorge


On Tue, Jul 7, 2009 at 3:06 PM, Mark Knecht <markknecht@gmail.com> wrote:

> Hi,
>   I am apparently not understanding some nuance about either the use
> of subset or more likely my ability to test for a numerical match
> using '='. Which is it? Thanks in advance.
>
>   I've read a data file, reshaped it and then created MyResults by
> keeping only lines where the value column is greater than 0. So far so
> good. The data in MyResults looks good to me by eye.
>
>   The problem comes in when I try to further subset MyResults into
> two files, one with PosType=1 and the other with PosType=-1. Looking
> at the dimension of the results there's no change. It didn't work
> which is verified by eye. However if I test for PosType=1 by actually
> testing for PosType>0 then it does work.
>
>   Is this the general case in R that if I've read data that was
> written into a csv file as 1 - it is 1 if I look into the file with a
> text editor - that I cannot test for that? Or is some case where I
> need to use maybe as.numeric or something else first to ensure R sees
> the number the way I'm thinking about the number?
>
> Cheers,
> Mark
>
> > dim(X)
> [1]  25 425
> >
> > ReShapeX <- melt(X, id = c("Trade", "PosType", "EnDate", "EnTime",
>  "ExDate",  "ExTime", "PL_Pos", "Costs", "Save2"))
> >
> > dim(ReShapeX)
> [1] 10400    11
> >
> > MyResults <- subset(ReShapeX, value > 0)
> >
> > dim(MyResults)
> [1] 1105   11
> >
> > MyResults.GroupA <- subset(MyResults, PosType = 1)
> >
> > dim(MyResults.GroupA)
> [1] 1105   11
> >
> > MyResults.GroupB <- subset(MyResults, PosType = -1)
> >
> > dim(MyResults.GroupB)
> [1] 1105   11
> >
> > MyResults.GroupA <- subset(MyResults, PosType > 0)
> >
> > dim(MyResults.GroupA)
> [1] 432  11
> >
> > MyResults.GroupB <- subset(MyResults, PosType < 0)
> >
> > dim(MyResults.GroupB)
> [1] 673  11
> >
>
> ______________________________________________
> R-help@r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>

	[[alternative HTML version deleted]]


