R help - May 2013 - Retrieve specific y for a list of x on a ploted line

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

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 r?rolle 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
>
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>