R ggplot输出中的图例错误

该代码的输出给出了一个分布和两条垂直线，一条红色，一条蓝色。但在图例中，蓝线标记为红色，反之亦然。原因可能是什么

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这是因为颜色由aes函数映射。如果您想手动映射它们，您可以像这样将它们从aes中取出

variances <- apply(matrix(rexp(40*1000,0.2),1000),1,var) 
hist(variances)
g <- ggplot(data.frame(x=variances), aes(x = x)) 
g <- g + geom_density(alpha=0.2,size=1,fill="red")
g <- g + geom_vline(aes(xintercept = mean(variances)), color="red", size=1) 
g <- g + geom_vline(aes(xintercept = (v_theo)), color="blue", size=1) 
g

请参见此处：

variances <- apply(matrix(rexp(40*1000,0.2),1000),1,var) 
hist(variances)
g <- ggplot(data.frame(x=variances), aes(x = x)) 
g <- g + geom_density(alpha=0.2,size=1,fill="red")
g <- g + geom_vline(aes(xintercept = mean(variances)), color="red", size=1) 
g <- g + geom_vline(aes(xintercept = (v_theo)), color="blue", size=1) 
g

variances <- apply(matrix(rexp(40*1000,0.2),1000),1,var) 
hist(variances)
g <- ggplot(data.frame(x=variances), aes(x = x)) 
g <- g + geom_density(alpha=0.2,size=1,fill="red")
g <- g + geom_vline(aes(xintercept = mean(variances),color="red"), size=1) 
g <- g + geom_vline(aes(xintercept = (v_theo),color="blue"), size=1) 
g <- g + scale_color_manual(values = c("blue", "red"))
g

library(ggplot2)
variances <- apply(matrix(rexp(40*1000,0.2),1000),1,var) 
hist(variances)
v_theo <- 45


g <- ggplot(data.frame(x=variances), aes(x = x)) 
g <- g + geom_density(alpha=0.2,size=1,fill="red")
g <- g + geom_vline(aes(xintercept = v_theo, color="blue"), size=1) 
g

g <- ggplot(data.frame(x=variances), aes(x = x)) 
g <- g + geom_density(alpha=0.2,size=1,fill="red")
g <- g + geom_vline(aes(xintercept = mean(variances),color="mean"), size=1) 
g <- g + geom_vline(aes(xintercept = v_theo,color="v_theo"), size=1) +
  scale_color_manual(name = "Legend name", values = c(mean = "red", v_theo = "blue"))
g