[R] Plot, lines and disordered x and y

[Todor Kondic]

Wow! More than I expected. I didn't try it, but seems convincing!

TK

2009/1/23 Jorge Ivan Velez <jorgeivanvelez at gmail.com>:
>
> Dear Todor,
> How about this?
> x<-c(1,-1,2,-2,3,-3,4,-4,5,-5)
> y<-c(1,0,2,0,3,0,4,0,5,0)
> DF<-data.frame(x,y)
> plot(with(DF,DF[order(x),]),type='o')
> HTH,
>
> Jorge
>
>
> On Fri, Jan 23, 2009 at 1:41 PM, Todor Kondic <dolichenus at gmail.com> wrote:
>>
>> Ok, here is a bit more information:
>>
>> R is version 2.7.1 (2008-06-23)
>>
>> A constructed example:
>> ....
>> > x<-c(1,-1,2,-2,3,-3,4,-4,5,-5)
>> > y<-c(1,0,2,0,3,0,4,0,5,0)
>> > plot(x,y,type='l')   #bad
>> > plot(x,y) # this is how it should look like
>> ....
>>
>> So what we should see here is a flat y=0 for x<0 and identity for x>0.
>> Instead, we have a saw-like shape where e.g y(x=-1) is connected to
>> y(x=1) .
>>
>> This is of course minor  (actually asymptotically, no annoyance at
>> all). I am just mentioning it for 'completness' sake and because a
>> divinely ideal plotting function should cope with data given in any
>> order.
>>
>> Cheers!
>>
>> TK
>>
>> Cheers,
>>
>> TK
>>
>>
>>
>> 2009/1/23 jim holtman <jholtman at gmail.com>:
>> > PLEASE do read the posting guide
>> > http://www.R-project.org/posting-guide.html
>> > and provide commented, minimal, self-contained, reproducible code.
>> >
>> > A sample of data causing the problem would help.  It is most likely
>> > the way you have it specified.
>> >
>> > On Fri, Jan 23, 2009 at 11:37 AM, Todor Kondic <dolichenus at gmail.com>
>> > wrote:
>> >> Hello,
>> >>
>> >> I have 2d data where x coordinate is not given in usual ascending
>> >> order (x1,...,x1+l; l>0), and instead in another, regular, but not
>> >> ascending or descending order (for illustration:
>> >> x1,-x1,x1+dx1,-x1-dx1,....).y is an array which corresponds to the way
>> >> x is ordered. I have noticed that giving 'plot(x,y,type='l') produces
>> >> a plot where the points are connected in a completely wrong way. It is
>> >> as the plot/lines assumes an ascending order between the succesive y
>> >> points ignoring the fact that they are not (it connects y(x1) with
>> >> y(-x1), for x1+dx). I don't know whether this could be a bug, because
>> >> maybe sorting the y coordinates appropriately and then interpolating
>> >> lines plotting is too much to ask of the plot function. But, I've felt
>> >> like sharing :-)
>> >>
>> >> Additionally, 'points' function will plot the data properly.
>> >>
>> >> Cheers,
>> >>
>> >> TK
>> >>
>> >> ______________________________________________
>> >> R-help at 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.
>> >>
>> >
>> >
>> >
>> > --
>> > Jim Holtman
>> > Cincinnati, OH
>> > +1 513 646 9390
>> >
>> > What is the problem that you are trying to solve?
>> >
>>
>> ______________________________________________
>> R-help at 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.
>
>