圖例文字顏色不會改變

Question

我用過這個代碼

plot.ecdf(subset(d.pizza, area == "Camden")$delivery_min, 
          col = "red", main = "ECDF for pizza deliveries")
plot.ecdf(subset(d.pizza, area == "Westminster")$delivery_min, 
          add = TRUE, col = "blue")
plot.ecdf(subset(d.pizza, area == "Brent")$delivery_min, 
          add = TRUE, col = "green")
legend(x=50, y=0.4, legend=c("Camden", "Westiminster", "Brent"), col=c("red","blue","green") )

獲取此圖：在此處輸入圖像描述

但是正如您所看到的，圖例文本與我在代碼中編寫的顏色不匹配。 為什么？ 我該如何解決？

關於這段代碼的同樣的事情

plot(density(subset(d.pizza, area == "Camden")$delivery_min), col="red", ylim=c(0,0.06)) 
  lines(density(subset([d.pizza, area == "Westminster")$delivery_min), col="blue") 
  lines(density(subset(d.pizza, area == "Brent")$delivery_min), col="green")
legend(x=50, y=0.05, legend=c("Camden", "Westiminster", "Brent"), col=c("red","blue","green") )

在此處輸入圖片說明

一定是犯了同樣的錯誤.. 提前致謝！

d.pizza id 來自“DescTools”包的數據框

Answer 1

您需要在圖例中添加一種要繪制的符號，以便可以對其進行着色：

legend(x=50, y=0.4, legend=c("Camden", "Westiminster", "Brent"), col=c("red","blue","green"), pch=1) #pch sets the type of point to be drawn

Answer 2

解決方案 1：使用 fill 而不是 col

legend(x=50, y=0.4, legend=c("Camden", "Westiminster", "Brent"), 
   fill=c("red","blue","green") )

解決方案2：使用pch

legend(x=50, y=0.4, legend=c("Camden", "Westiminster", "Brent"), 
   col=c("red","blue","green"), pch=16 )