[R] Add Gauss normal curve ?

[Daniel Nordlund]

Just replace 'mean(y)' in your curve() function with 
as.Date("whatever-date")

curve(n*dnorm(x, as.Date("2020-03-30"), sd(y)), add=TRUE, col="red", lwd=2)

Dan

On 4/11/2020 8:36 AM, varin sacha via R-help wrote:
> Dear Peter,
> Dear David,
>
> Many thanks for your response.
> Indeed, counts do not have a Gaussian distribution, even if.... sometimes one approximates the distribution by a Gaussian one, usually using the argument of the Central Limit Theorem.
>
> Here below the reproducible example.
> One last thing. Now if I want to move my red Gaussian curve to the right or to the left, for example on the graph I can see that the Gaussian curve is centered around the 5th of April.
>
> Is it possible to move the Gaussian curve to make the center of the Gaussian curve on the 30th of March for example ? If yes, how to do ?
>
> ############################################################
> mydates <- as.Date(c("2020-03-15", "2020-03-16","2020-03-17","2020-03-18","2020-03-19","2020-03-20","2020-03-21","2020-03-22","2020-03-23","2020-03-24","2020-03-25","2020-03-26","2020-03-27","2020-03-28","2020-03-29","2020-03-30","2020-03-31","2020-04-01","2020-04-02","2020-04-03","2020-04-04","2020-04-05","2020-04-06","2020-04-07","2020-04-08","2020-04-09","2020-04-10"))
>
> nc<-c(1,1,2,7,3,6,6,20,17,46,67,71,56,70,85,93,301,339,325,226,608,546,1069,1264,1340,813,608)
>
> plot(as.Date(mydates),nc,pch=16,type="o",col="blue",ylim=c(1,1400), xlim=c(min(as.Date(mydates)),max(as.Date(mydates))))
>
> y <- rep(mydates, nc)
> n <- sum(nc)
> curve(n*dnorm(x, mean(y), sd(y)), add=TRUE, col="red", lwd=2)
> ############################################################
>
>
>
>
>
>
>
> Le samedi 11 avril 2020 à 17:02:36 UTC+2, peter dalgaard <pdalgd using gmail.com> a écrit :
>
>
>
>
>
> Two obvious problems:
>
> 1. mean(nc) is a count, not a date, sd likewise
> 2. the scale of dnorm() is density, not count
>
> So (slightly inefficient, but who cares...):
>
> y <- rep(mydates, nc)
> n <- sum(nc)
> curve(n*dnorm(x, mean(y), sd(y)), add=TRUE, col="red", lwd=2)
>
> -pd
>
>> On 11 Apr 2020, at 16:00 , varin sacha via R-help <r-help using r-project.org> wrote:
>>
>> Dear R-experts,
>>
>> Here below my reproducible example. I would like to fit/add the Gauss normal curve to this data.
>> I don't get it. There is no error message but I don't get what I am looking for.
>> Many thanks for your help.
>>
>> ############################################################
>> mydates <- as.Date(c("2020-03-15", "2020-03-16","2020-03-17","2020-03-18","2020-03-19","2020-03-20","2020-03-21","2020-03-22","2020-03-23","2020-03-24","2020-03-25","2020-03-26","2020-03-27","2020-03-28","2020-03-29","2020-03-30","2020-03-31","2020-04-01","2020-04-02","2020-04-03","2020-04-04","2020-04-05","2020-04-06","2020-04-07","2020-04-08","2020-04-09","2020-04-10"))
>>
>> nc<-c(1,1,2,7,3,6,6,20,17,46,67,71,56,70,85,93,301,339,325,226,608,546,1069,1264,1340,813,608)
>>
>> plot(as.Date(mydates),nc,pch=16,type="o",col="blue",ylim=c(1,1400), xlim=c(min(as.Date(mydates)),max(as.Date(mydates))))
>>
>> x <- seq(min(mydates), max(mydates), 0.1)
>>
>> curve(dnorm(x, mean(nc), sd(nc)), add=TRUE, col="red", lwd=2)
>> ############################################################
>>
>> ______________________________________________
>> R-help using r-project.org mailing list -- To UNSUBSCRIBE and more, see
>> 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.
>

-- 
Daniel Nordlund
Port Townsend, WA  USA