如何繪製組內的非線性迴歸線和ggplot2中的總數據？

Question

我有一個簡單的數據有兩個連續變量（囊泡和細胞），並用兩個級別（HC和RA）的單個分組變量設置，這裏模擬：

###Simulate Vesicle variable### 
Vesicle.hc <- sort(runif(23, 0.98, 5)) #HC group 
Vesicle1.ra <- sort(runif(5, 0.98, 3)) #RA group 
Vesicle <- c(Vesicle.hc, Vesicle1.ra) #Combined 

###Simulate Cells variable### 
z <- seq(23) 
Cells.hc <- (rnorm(23, 50 + 30 * z^(0.2), 8))*runif(1, 50000, 400000) #HC group 
Cells.ra <- c(8.36e6, 6.35e6, 1.287e7, 1.896e7, 1.976e7)    #RA group 
Cells <- c(Cells.hc, Cells.ra)           #Combined 

###Define groups and create dataframe### 
Group <- rep("HC",23)        #HC group 
Group1 <- rep("RA",5)        #RA Group 
Group <- c(Group, Group1)       #Combined 
df <- data.frame(Cells, Vesicle, Group)    #Data frame 

我已經繪製的數據的散點圖使用GGPLOT2與非線性迴歸線（示here），裝配到各組個別地使用：

###Plot data### 
library(ggplot2) 
ggplot(df, aes(x = Cells, y = Vesicle, colour=Group)) + 
    xlab("Stimulated neutrophils") + 
    ylab("MV/cell") + 
    stat_smooth(method = 'nls', formula = 'y~a*exp(b*x)',      #Fit nls model 
       method.args = list(start=c(a=0.1646, b=9.5e-8)), se=FALSE) + #Starting values 
    geom_point(size=4, pch=21,color = "black", stroke=1.5, aes(fill=Group)) #Change point style 

我的問題是，除了繪製每組的非線性迴歸函數，哪能還情節一個迴歸線適合於所有全部數據即對數據建模忽略分組變量的貢獻？

Answer 1

ggplot(df, aes(x = Cells, y = Vesicle, colour=Group)) + 
    xlab("Stimulated neutrophils") + 
    ylab("MV/cell") + 
    stat_smooth(method = 'nls', formula = 'y~a*exp(b*x)', 
       method.args = list(start=c(a=0.1646, b=9.5e-8)), se=FALSE) + 
    stat_smooth(color = 1, method = 'nls', formula = 'y~a*exp(b*x)', 
       method.args = list(start=c(a=0.1646, b=9.5e-8)), se=FALSE) + 
    geom_point(size=4, pch=21,color = "black", stroke=1.5, aes(fill=Group))