ggplot 图例顺序不匹配

Question

我是 R/ggplot 的新手，我已经针对调查了 Whosebug，但无济于事。估计是屋里的ggplot高手们的小问题，如果是的话，期待快速解答！

所以这里是：我正在尝试根据存储在数据框中的变量绘制 4 条曲线，同时使用颜色和线型。不幸的是，图例标签与曲线不匹配，这违背了图例的全部目的。

下图：

这是生成它的代码：

# declare variables
alpha = 0.5
m = 500
x = seq(m)
fdr_thresh = x/m*alpha
lvl_thresh = rep(alpha,m)
pvals = sin(2*pi*x/20)
pvalsA = exp(-x/100)*cos(2*pi*x/20)

# plot
df <- data.frame(pvals=pvals, pvalsA = pvalsA, FDR = fdr_thresh, level = lvl_thresh, x=x)
p4 <- ggplot(data = df) + geom_line(aes(x=x, y=pvals,color="Pure Sinusoid",linetype="Pure Sinusoid"))
p4 <- p4 + geom_line(aes(x=x, y=pvalsA,color="Damped Sinusoid",linetype="Damped Sinusoid"))
p4 <- p4 + geom_line(aes(x=x, y=FDR,color = 'FDR', linetype='FDR')) 
p4 <- p4 + geom_line(aes(x=x, y=level,color='alpha',linetype='alpha'))  
p4 = p4+ scale_linetype_manual(name = "Significance", values=c("Pure Sinusoid"= 1,"Damped Sinusoid" = 1,"FDR" = 2,"alpha" = 3),labels=c("Pure Sinusoid", "Damped Sinusoid", "Sloping line",bquote(alpha == .(alpha))))
p4 = p4 + scale_color_manual(name = "Significance",values=c("Pure Sinusoid"= "Chocolate1","Damped Sinusoid" = 'Chartreuse4',"FDR" = "black","alpha" = "black") , labels=c("Pure Sinusoid", "Damped Sinusoid", "Sloping line",bquote(alpha == .(alpha))))
p4 <- p4 +  theme(legend.position = c(0.7, 0.8),legend.title=element_blank(),legend.key = element_rect(fill = "transparent",colour = "transparent"),legend.background = element_rect(fill=alpha('white', 0.8)))
show(p4)

如果能提供有关如何做得更好的提示，我将不胜感激。同样的情节在 Matlab 或 Python 中是正确的，并且花费了 15 分钟，所以我一定是在某个地方做出了错误的决定。（不，选择 R 并不是那个决定：这是我学习它的一部分努力）

Answer 1

这样做的 "right way" 是将您的数据集融入一个长数据框，然后让 ggplot 负责为您绘制多条线，而不是单独发布 geom_line() 调用 ...

# plot
df <- data.frame(pvals, pvalsA, FDR = fdr_thresh, level = lvl_thresh, x)

mm <- reshape2::melt(df,id.var="x")
my.labs <- c("Pure Sinusoid","Damped Sinusoid","Sloping line",
           bquote(alpha==.(alpha)))
p4 <- ggplot(data = mm, aes(x,value,colour=variable,linetype=variable)) +
    geom_line()
p4 <- p4 + scale_linetype_manual(name="Significance",values=c(1,1,2,3),
          labels=my.labs)
p4 <- p4 + scale_color_manual(name = "Significance",
                  values=c("Chocolate1",'Chartreuse4',"black","black"),
                  labels=my.labs)
p4 <- p4 +  theme(legend.position = c(0.7, 0.8),
                  legend.title=element_blank(),
                  legend.key = element_rect(fill = "transparent",
                                            colour = "transparent"),
          legend.background = element_rect(fill=alpha('white', 0.8)))
show(p4)

（我已经在我工作的 R 会话中设置了 theme_bw()，这就是为什么缺少灰色 background/grid 行的原因......）

Answer 2

问题是您在映射变量标签时添加了错误的顺序。

dp4 <- ggplot(data = df) + geom_line(aes(x=x, y=pvals,color="Pure Sinusoid",linetype="Pure Sinusoid"))
p4 <- p4 + geom_line(aes(x=x, y=pvalsA,color="Damped Sinusoid",linetype="Damped Sinusoid"))
p4 <- p4 + geom_line(aes(x=x, y=FDR,color = 'FDR', linetype='FDR')) 
p4 <- p4 + geom_line(aes(x=x, y=level,color='alpha',linetype='alpha'))  

p4 <- p4+ scale_linetype_manual(name = "Significance", values=c("Pure Sinusoid"= 1,"Damped Sinusoid" = 1,"FDR" = 2,"alpha" = 3),labels=c(bquote(alpha == .(alpha)), "Damped Sinusoid", "Sloping line","Pure Sinusoid"))

p4 <- p4 + scale_color_manual(name = "Significance",values=c("Pure Sinusoid"= "Chocolate1","Damped Sinusoid" = 'Chartreuse4',"FDR" = "black","alpha" = "black") , labels=c(bquote(alpha == .(alpha)), "Damped Sinusoid", "Sloping line","Pure Sinusoid"))

p4 <- p4 +  theme(legend.position = c(0.7, 0.8),legend.title=element_blank(),legend.key = element_rect(fill = "transparent",colour = "transparent"),legend.background = element_rect(fill=alpha('white', 0.8)))
show(p4)

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