[R] howto find corresponding values in datasource?

[bartjoosen]

The x coordinate of the max y value:

x[which.max(mydiff$y)]




Jonas Stein wrote:
> 
> Hi,
> 
> 
> i am sure, that this is a noob-question, but i have searched for 
> hours without any good result. 
> 
> I want to draw a vertical line through the maximum of the first
> derivation.
> 
> Here is a small example. 
> 
> --8<-----[mydata.csv]--------------------------------
> H    M
> 1    15
> 2    22
> 3    23
> 4    17
> 5    10
> --8<-----[myquestion.R]------------------------------
> mydata <- read.table("mydata.csv", header=TRUE, sep="\t")
> 
> attach(mydata)
> # make a smooth fit through the points and calculate the first derivation
> d/dx
> myspl <- smooth.spline(H, M, all.knots = FALSE, nknots = 10, spar=0.5) 
> mydiff <- predict(myspl, 0:max(H), deriv=1)
> 
> 
> # find the maximum peak max(y)
> y1=y2= max(mydiff$y)
> 
> # now i want to plot a line through the maximum of the derivation
> # how can i get the x-coordinate?
> # segments(x1,y1,x2,y2)
> 
> detach()
> --8<-------------------------------------
> 
> Thank you,
> 
> -- 
> Jonas Stein
> 
> ______________________________________________
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> 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.
> 
> 

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