On Aug 29, 2010, at 10:50 PM, Erik Ramberg wrote:
I'm a newbie to R and I was hoping someone could answer a simple
question. I want to read in an ASCII file with 3 columns - x,y,z.
Let's say there is a lot of data - 100,000 entries. I then want to
histogram x values that pass arbitrary (and complicated) cuts on y
and/or z. Likewise, I want to make a scatterplot with x and y, with
a cut on z values. Perhaps you have to redefine the vectors first.
I'm thinking along the lines of
hist(x) for y>0 .and. sqrt(z)<4
If the data is in a dataframe named dta with columns x,y, and z then:
with( dta[which( dta$y > 0 & sqrt(z) < 4), ],
hist(x) )
or
plot(x,y) for x>0 .and. y>0 .and.z**2 > 100
The strategy generalizes.
I cant find this simple task in a first perusal of some of the
tutorials.
Any suggestions you could give would be helpful.
Don't forget to read the Posting Guide.
--
David.
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