GGPLOT2：繪製迴歸線與不同的攔截，但與相同的斜率

Question

我想繪製迴歸線與不同的攔截，但具有相同的斜率。

用下面ggplot2代碼，我可以繪製迴歸曲線與不同截距和不同的斜率。但無法弄清楚如何繪製具有不同截距但不同斜率的迴歸線。任何幫助將不勝感激。由於

library(ggplot2) 
    ggplot(data=df3, mapping=aes(x=Income, y=Consumption, color=Gender)) + geom_point() + 
    geom_smooth(data=df3, method = "lm", se=FALSE, mapping=aes(x=Income, y=Consumption)) 

Consumption <- c(51, 52, 53, 54, 56, 57, 55, 56, 58, 59, 62, 63) 
Gender <- gl(n = 2, k = 6, length = 2*6, labels = c("Male", "Female"), ordered = FALSE) 
Income <- rep(x=c(80, 90, 100), each=2) 
df3 <- data.frame(Consumption, Gender, Income) 
df3 

# Regression with same slope but different intercepts for each Gender 
fm1 <- lm(formula=Consumption~Gender+Income, data=df3) 
summary(fm1) 

Call: 
lm(formula = Consumption ~ Gender + Income, data = df3) 

Residuals: 
    Min  1Q Median  3Q  Max 
-0.8333 -0.8333 0.1667 0.1667 1.1667 

Coefficients: 
      Estimate Std. Error t value Pr(>|t|)  
(Intercept) 26.83333 2.54557 10.54 2.30e-06 *** 
GenderFemale 5.00000 0.45812 10.91 1.72e-06 *** 
Income  0.30000 0.02805 10.69 2.04e-06 *** 
--- 
Signif. codes: 0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1 

Residual standard error: 0.7935 on 9 degrees of freedom 
Multiple R-squared: 0.9629, Adjusted R-squared: 0.9546 
F-statistic: 116.7 on 2 and 9 DF, p-value: 3.657e-07 

Answer 1

你爲什麼不計算迴歸的結果ggplot之外從lm：

# Regression with same slope but different intercepts for each Gender 
fm1 <- lm(formula=Consumption~Gender+Income, data=df3) 
df3 = cbind(df3, pred = predict(fm1)) 

ggplot(data=df3, mapping=aes(x=Income, y=Consumption, color=Gender)) + geom_point() + 
    geom_line(mapping=aes(y=pred)) 

主要生產相同的斜率和截距不同：

從技術上講，你在看您的模型沒有兩個不同的截距，但是對虛擬變量GenderFemale有額外的偏移量。

編輯：包括predict簡化，這要歸功於@aosmith用於建議。