[R] [GGplot] Geom_smooth with formula "power"?

[Catarina Silva]

I've tried others initial solutions and the adjustement was done to power model in ggplot - geom_smooth.
But, with "nls" I can't do the confidence interval with ggplot - geom_smooth? I read that with "nls" we have to force "se=FALSE". Is this true?
How can I draw confidence interval in the plot?

I've done this:
> ggplot(data,aes(x = idade,y = v_mt)) +
+   geom_point(alpha=2/10, shape=21,fill="darkgray", colour="black", size=3) + 
+   geom_smooth(method = 'nls', formula = y ~ a * x^b, start = list(a=1,b=2),se=FALSE) 
>
And then I don't have the confidence interval.

If I do:
> ggplot(data,aes(x = idade,y = v_mt)) +
+   geom_point(alpha=2/10, shape=21,fill="darkgray", colour="black", size=3) + 
+   geom_smooth(method = 'nls', formula = y ~ a * x^b, start = list(a=1,b=2)) 
Error in pred$fit : $ operator is invalid for atomic vectors
>

Return error...

Ty,
Catarina Silva  

-----Original Message-----
From: Jeff Newmiller [mailto:jdnewmil at dcn.davis.CA.us] 
Sent: sábado, 7 de Novembro de 2015 01:09
To: bolseiro.raiz.csilva at portucelsoporcel.com; R mailling list
Subject: Re: [R] [GGplot] Geom_smooth with formula "power"?

Does  [1] help? 

[1] http://stackoverflow.com/questions/10528631/add-exp-power-trend-line-to-a-ggplot
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On November 6, 2015 2:41:18 AM PST, Catarina Silva <bolseiro.raiz.csilva at portucelsoporcel.com> wrote:
>Hi,
>
>It's possible to use ggplot and geom_smooth to adjust a power curve to 
>the data?
>
>Initially i have done the adjustement with nls and the formula 'a*x^b', 
>but resulted the singular matrix error for start solution. 
>Alternatively I used the log transformation and i had correct results, 
>but I can't draw a power curve on the graphic.
>
>Someone know how to solve this problem?
>
> 
>
>Ty,
>
> 
>
>Catarina Silva
>
>
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--------------------------
Print on our paper - Care for the environment.
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