[R-sig-eco] lines() adds extra line

Jane Shevtsov jane.eco at gmail.com
Mon Jan 24 19:46:03 CET 2011


Thanks; that works!

Best,
Jane

On Mon, Jan 24, 2011 at 10:15 AM, Sarah Goslee <sarah.goslee at gmail.com> wrote:
> R is doing just as you asked. If you look at the middle of c(x, x) the
> x values jump from 10 to -10 and R draws the line segment connecting
> them, as it's been told.
>
>> c(x,x)[195:205]
>  [1]   9.4   9.5   9.6   9.7   9.8   9.9  10.0 -10.0  -9.9  -9.8  -9.7
>
> You might rather have:
>> x2.rev <- c(x, rev(x))
>> x.rev.pred <- predict(lm(dataBoth.poly ~ x2.rev + I(x2.rev^2)+I(x2.rev^3)+I(x2.rev^4)+I(x2.rev^5)+I(x2.rev^6)))
>> plot(x2.rev, x.rev.pred, type="l")
>
> Sarah
>
>
> On Mon, Jan 24, 2011 at 1:04 PM, Jane Shevtsov <jane.eco at gmail.com> wrote:
>> I'm trying a bit of an experiment with polynomial curve fitting (don't
>> worry, I wouldn't do this to actual data -- it's just a toy model for
>> a specific question). When I generate a linear model of the data and
>> plot it using plot(), everything works fine. But when I use plot(...,
>> type="l") or lines(), I get an extra line connecting two points. How
>> do I stop this from happening?
>>
>> Here's the code:
>> x = seq(-10, 10, by=0.1)
>> data1poly <- 0.1*x + 0.2*x^2 + 0.3*x^3 + 0.4*x^4 + 0.5*x^5 + 0.6*x^6 +
>> 0.7 + rnorm(length(x),1E-3, 1E-4)
>> data2poly <- 0.1*x + 0.2*x^2 + 0.3*x^3 + 0.4*x^4 + 0.5*x^5 + 0.6*x^6 -
>> 1 + rnorm(length(x), 1E-3, 1E-4)
>> dataBoth.poly <- c(data1poly, data2poly)
>> #Works well
>> plot(c(x,x), predict(lm(dataBoth.poly ~ c(x,x) +
>> I(c(x,x)^2)+I(c(x,x)^3)+I(c(x,x)^4)+I(c(x,x)^5)+I(c(x,x)^6))))
>> #Adds extra line
>> plot(c(x,x), predict(lm(dataBoth.poly ~ c(x,x) +
>> I(c(x,x)^2)+I(c(x,x)^3)+I(c(x,x)^4)+I(c(x,x)^5)+I(c(x,x)^6))),
>> type="l")  #or
>> lines(c(x,x), predict(lm(dataBoth.poly ~ c(x,x) +
>> I(c(x,x)^2)+I(c(x,x)^3)+I(c(x,x)^4)+I(c(x,x)^5)+I(c(x,x)^6))))
>>
>> Thanks,
>> Jane
>>
>> --
>
> --
> Sarah Goslee
> http://www.functionaldiversity.org
>



-- 
-------------
Jane Shevtsov
Ecology Ph.D. candidate, University of Georgia
co-founder, <www.worldbeyondborders.org>
Check out my blog, <http://perceivingwholes.blogspot.com>Perceiving Wholes

"The whole person must have both the humility to nurture the
Earth and the pride to go to Mars." --Wyn Wachhorst, The Dream
of Spaceflight



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