R help - Mar 2019 - Obtaining individual parameters from a sitar growth model.

I want to obtain the individual biological parameters (ie age at takeoff,
final height velocity at takeoff) after a sitar model. (I do understand a
sitar model fits a mean curve for the population).



I have managed to obtain the parameters for one individual using the code
below,





library(sitar)

data(heights)

library(tidyverse)

m1 <- sitar(x=age, y=height, id=id, data=heights, df=5)



#velocity at takeoff for individual 1



(vel_attoff<-getPeakTrough(plot_v(m1, subset=age < 14 & id==1) ,
peak=FALSE))





What I want is to produce a dataframe with the id and the velocity at
takeoff for each individual in the dataset.



I have tried to do this



for (i in seq_along(heights[1])){

                print(getPeakTrough(plot_v(m1, subset=age < 14 & id==i) ,
peak=FALSE))

}



But it prints only one x and y  value



Any assistance will be greatly appreciated.


-- 
R T CHIRUKA
University of Fort Hare
Statistics Department
Box X 1314
Alice
5700
South Africa

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