使用ggplot的非线性模型绘图问题

问题描述

我在通过 stat_smooth 绘制 NLS 拟合时遇到问题。有趣的是，拟合曲线在负 y 方向移动。有谁知道这可能是什么原因？下面是代码、数据和示例图（URL）：

y<-c(0.686,0.674,0.631,0.580,0.520,0.440,0.411,0.401,0.338,0.262,0.218,0.703,0.628,0.584,0.547,0.513,0.457,0.395,0.372,0.326,0.255,0.213,0.760,0.684,0.622,0.577,0.550,0.463,0.352,0.311,0.244,0.212)
x<-c(0.03,0.08,0.15,0.23,0.30,0.75,1.50,2.25,3.01,7.52,15.03,0.03,15.03)  
df<-as.data.frame(cbind(x,y)) 
ggplot(df,aes(x=x,y=y))+
  geom_point()+
  stat_smooth(method = "nls",formula = log10(y) ~ c1*log10(x)+c2,method.args=list(start=list(c1=-0.2,c2=-0.4)),se=FALSE)

非常感谢 XEZ

解决方法

就像评论中提到的 stefan 一样，那是因为你适合 log10(y)。转换输入值的另一种解决方案是在计算拟合后反转对数转换。您可以使用 stage() 函数执行此操作：

library(ggplot2)

y<-c(0.686,0.674,0.631,0.580,0.520,0.440,0.411,0.401,0.338,0.262,0.218,0.703,0.628,0.584,0.547,0.513,0.457,0.395,0.372,0.326,0.255,0.213,0.760,0.684,0.622,0.577,0.550,0.463,0.352,0.311,0.244,0.212)
x<-c(0.03,0.08,0.15,0.23,0.30,0.75,1.50,2.25,3.01,7.52,15.03,0.03,15.03)  
df<-as.data.frame(cbind(x,y)) 
ggplot(df,aes(x=x,y=y))+
  geom_point()+
  stat_smooth(method = "nls",formula = log10(y) ~ c1*log10(x)+c2,method.args=list(start=list(c1=-0.2,c2=-0.4)),aes(y = stage(y,after_stat = 10^y)),se=FALSE)

^{由 reprex package (v1.0.0) 于 2021 年 6 月 29 日创建}

ggplot2 nls r r smoothing