[R] Not the same length

[peter dalgaard]

Um, I think not... The mean of the last 200 observation won't line up with the x and z. 

Possibly, if what you want is the last 200 obs to have a different variance, 

y_obs <- y_model + c(rnorm(0.9 * n, 0, 0.1), rnorm(0.1 * n, 0, 0.5))

or

y_obs <- rnorm(n, y_model, rep(c(0.1, 0.5), c(.9 * n, .1 * n)))

-pd


> On 17 Sep 2019, at 22:27 , David Winsemius <dwinsemius using comcast.net> wrote:
> 
> 
> On 9/17/19 12:48 PM, varin sacha via R-help wrote:
>> Dear R-helpers,
>> 
>> Doing dput(x) and dput(y_obs), the 2 vectors are not the same length (1800 for y_obs and 2000 for x)
>> How can I solve the problem ?
>> 
>> Here is the reproducible R code
>> 
>>   #  #  #  #  #  #  #  #  #  #
>> library(mgcv)
>>  library(earth)
>> 
>> n<-2000
>> x<-runif(n, 0, 5)
>>  y_model<- 0.1*x^3 - 0.5 * x^2 - x + 10
>> # y_obs<-rnorm(n*0.9, y_model, 0.1)+rnorm(n*0.1, y_model, 0.5) # maybe not exactly your goal?
> 
> 
> You didn't lay out any goals for analysis, so let me guess what was intended:
> 
> 
> I suspect that you were hoping to model a mixture composed of 90% from one distribution and 10% from another. If I'm right about that guess then you would instead wat to join the samples from each distribution:
> 
> y_obs<-c( rnorm(n*0.9, y_model, 0.1),  rnorm(n*0.1, y_model, 0.5) )
> 
> -- 
> 
> David
> 
> 
>> gam_model<- gam(y_obs~s(x))
>> mars_model<- earth(y_obs~x)
>> MSE_GAM<-mean((gam_model$fitted.values - y_model)^2)
>> MSE_MARS<-mean((mars_model$fitted.values - y_model)^2)
>> MSE_GAM
>> MSE_MARS
>>   #  #  #  #  #  #  #  #  #  #  #  #  #  #  #  #
>> 
>> ______________________________________________
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> 
> ______________________________________________
> R-help using r-project.org mailing list -- To UNSUBSCRIBE and more, see
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> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.

-- 
Peter Dalgaard, Professor,
Center for Statistics, Copenhagen Business School
Solbjerg Plads 3, 2000 Frederiksberg, Denmark
Phone: (+45)38153501
Office: A 4.23
Email: pd.mes using cbs.dk  Priv: PDalgd using gmail.com