Re: [R] by() subset by factor gives unexpected results
Putting answer here for future posterity. Didn't send to R-help initially
because I wasn't sure
what OP wanted. I guessed right. Sorry for confusion in thread.
GUESSING THAT YOU WANT IS BELOW
#===
i <- data.frame(x=c(1,2,3), y=c(0,0,0), B=c("red","blue","blue"),
stringsAsFactors = FALSE)
j <- data.frame(x=c(1,2,3), y=c(1,1,1), B=c('red','blue','green'),
stringsAsFactors = FALSE)
plot(0, 0, type="n", xlim=c(0,4), ylim=c(0,1))
points(i$x, i$y, col = i$B)
points(j$x, j$y, col = j$B)
On Sat, Aug 5, 2017 at 5:59 AM, Myles English
wrote:
>
> The answer was (thanks to Mark Leeds) to do with the use of a factor
> instead of a vector.
>
> on [2017-08-05] at 08:57 Myles English writes:
>
> > I am having trouble understanding how the 'by' function works. Using
> > this bit of code:
> >
> > i <- data.frame(x=c(1,2,3), y=c(0,0,0), B=c("red","blue","blue"))
> > j <- data.frame(x=c(1,2,3), y=c(1,1,1), B=c('red','blue','green'))
>
> The use of I() prevents conversion to a factor:
>
> i <- data.frame(x=c(1,2,3), y=c(0,0,0), B=I(c("red","blue","blue")))
> j <- data.frame(x=c(1,2,3), y=c(1,1,1), B=I(c('red','blue','green')))
>
> > plot(0, 0, type="n", xlim=c(0,4), ylim=c(0,1))
> > by(i, i$B, function(s){ points(s$x, s$y, col=s$B) })
> > by(j, j$B, function(s){ points(s$x, s$y, col=s$B) })
> >
> > I would have expected the point at (1,1) to be coloured red. When
> > plotted, this row is indeed red:
> >
> >> i[1,]
> > x y B
> > 1 1 0 red
> >
> > however, this next point is green on the plot even though I would like
> > it to be red:
> >
> >> j[1,]
> > x y B
> > 1 1 1 red
> >
> > How can I achieve that?
> >
> > Myles
>
>
[[alternative HTML version deleted]]
__
R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see
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.
Re: [R] by() subset by factor gives unexpected results
... and, of course, by() should not be used at all for this sort of
thing in practice, as the "col" argument can be a vector. See
?plot.default if you you were not aware of this already.
j <- data.frame(x=c(1,2,3), y=c(1,1,1), B=c("red","blue","green"),
stringsAsFactors = FALSE)
with(j,plot(x,y, col=B, xlim=c(0,4), ylim=c(0,1.2)))
Cheers,
Bert
Bert Gunter
"The trouble with having an open mind is that people keep coming along
and sticking things into it."
-- Opus (aka Berkeley Breathed in his "Bloom County" comic strip )
On Sat, Aug 5, 2017 at 2:59 AM, Myles English wrote:
>
> The answer was (thanks to Mark Leeds) to do with the use of a factor
> instead of a vector.
>
> on [2017-08-05] at 08:57 Myles English writes:
>
>> I am having trouble understanding how the 'by' function works. Using
>> this bit of code:
>>
>> i <- data.frame(x=c(1,2,3), y=c(0,0,0), B=c("red","blue","blue"))
>> j <- data.frame(x=c(1,2,3), y=c(1,1,1), B=c('red','blue','green'))
>
> The use of I() prevents conversion to a factor:
>
> i <- data.frame(x=c(1,2,3), y=c(0,0,0), B=I(c("red","blue","blue")))
> j <- data.frame(x=c(1,2,3), y=c(1,1,1), B=I(c('red','blue','green')))
>
>> plot(0, 0, type="n", xlim=c(0,4), ylim=c(0,1))
>> by(i, i$B, function(s){ points(s$x, s$y, col=s$B) })
>> by(j, j$B, function(s){ points(s$x, s$y, col=s$B) })
>>
>> I would have expected the point at (1,1) to be coloured red. When
>> plotted, this row is indeed red:
>>
>>> i[1,]
>> x y B
>> 1 1 0 red
>>
>> however, this next point is green on the plot even though I would like
>> it to be red:
>>
>>> j[1,]
>> x y B
>> 1 1 1 red
>>
>> How can I achieve that?
>>
>> Myles
>
> __
> R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see
> 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.
__
R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see
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.
Re: [R] by() subset by factor gives unexpected results
The answer was (thanks to Mark Leeds) to do with the use of a factor
instead of a vector.
on [2017-08-05] at 08:57 Myles English writes:
> I am having trouble understanding how the 'by' function works. Using
> this bit of code:
>
> i <- data.frame(x=c(1,2,3), y=c(0,0,0), B=c("red","blue","blue"))
> j <- data.frame(x=c(1,2,3), y=c(1,1,1), B=c('red','blue','green'))
The use of I() prevents conversion to a factor:
i <- data.frame(x=c(1,2,3), y=c(0,0,0), B=I(c("red","blue","blue")))
j <- data.frame(x=c(1,2,3), y=c(1,1,1), B=I(c('red','blue','green')))
> plot(0, 0, type="n", xlim=c(0,4), ylim=c(0,1))
> by(i, i$B, function(s){ points(s$x, s$y, col=s$B) })
> by(j, j$B, function(s){ points(s$x, s$y, col=s$B) })
>
> I would have expected the point at (1,1) to be coloured red. When
> plotted, this row is indeed red:
>
>> i[1,]
> x y B
> 1 1 0 red
>
> however, this next point is green on the plot even though I would like
> it to be red:
>
>> j[1,]
> x y B
> 1 1 1 red
>
> How can I achieve that?
>
> Myles
__
R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see
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.
[R] by() subset by factor gives unexpected results
I am having trouble understanding how the 'by' function works. Using
this bit of code:
i <- data.frame(x=c(1,2,3), y=c(0,0,0), B=c("red","blue","blue"))
j <- data.frame(x=c(1,2,3), y=c(1,1,1), B=c('red','blue','green'))
plot(0, 0, type="n", xlim=c(0,4), ylim=c(0,1))
by(i, i$B, function(s){ points(s$x, s$y, col=s$B) })
by(j, j$B, function(s){ points(s$x, s$y, col=s$B) })
I would have expected the point at (1,1) to be coloured red. When
plotted, this row is indeed red:
> i[1,]
x y B
1 1 0 red
however, this next point is green on the plot even though I would like
it to be red:
> j[1,]
x y B
1 1 1 red
How can I achieve that?
Myles
__
R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see
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.
