[R] Retrieve specific y for a list of x on a ploted line

[Bert Gunter]

With the same possibility of misunderstanding as Rui, this sort of
question is generally answered by predict() methods, in this case:

?predict.smooth.spline


-- Bert

On Mon, May 6, 2013 at 8:26 AM, Rui Barradas <ruipbarradas at sapo.pt> wrote:
> Hello,
>
> I'm not sure I understand. If you assign the value of smooth.spline, you'll
> have a list with elements x and y:
>
> dat <- read.table(text = "
>  X     Y
> 1    0    137.659166666667
> 2    2.502    152.623333333333
> 3    4.998    162.391333333333
> 4    7.501    170.753666666667
> 5    9.997    174.877
> 6    12.499    178.4275
> 7    15.002 184.565
> 8    17.498    189.8985
> 9    20    192.6885
> ", header = TRUE)
> dat
>
> sp <- smooth.spline(dat)
> plot(sp$x, sp$y, type="l")
>
>
> Aren't the values of y you want in sp$y?
>
> Hope this helps,
>
> Rui Barradas
>
> Em 06-05-2013 14:36, camille rérolle escreveu:
>>
>> Dear list,
>>
>> I'm trying to retrieve specific y for a list of x on a drawn line in the
>> plot area.
>> The line is plot with an other list of xy coordinates,which only serve to
>> plot the line.
>> Here is an example of the beginning of a table of initial coordinates
>> which
>> permit to draw the line:
>>          X     Y
>> "1"    0    137.659166666667
>> "2"    2.502    152.623333333333
>> "3"    4.998    162.391333333333
>> "4"    7.501    170.753666666667
>> "5"    9.997    174.877
>> "6"    12.499    178.4275
>> "7"    15.002 184.565
>> "8"    17.498    189.8985
>> "9"    20    192.6885
>> [...]
>>
>> Here is what I want to do:
>>
>>          dossier<-  ### path of the table to read
>>          table <- read.table(dossier)
>>          curv<-plot(smooth.spline(table),
>> type="l",xlim=c(0,100),ylim=c(0,255))
>>
>>          # Now the line is drawn
>>
>>          #For x in 1:100 on  curv, I want to retrieve each
>> corresponding y and sort coordinates in a table.
>>
>> I search on the forum, the RSiteSearch, the R-intro.pdf, and I read the
>> book
>> of the most common graph packages...
>> But I don't find the specific answer for my problem.
>> Can you help me, please.
>> Kind regards
>>
>> Camille
>>
>> ______________________________________________
>> 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.
>>
>
> ______________________________________________
> 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.



-- 

Bert Gunter
Genentech Nonclinical Biostatistics

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