为条形图和线条创建一个共同的图例

Question

我对R很新，所以如果这是一个非常基本的问题，我会提前道歉。

我试图绘制一个显示排放和悬浮沉积物负荷（SSL）的图表。但是，我想清楚地表明条形图表示放电，线图表示SSL。我有两个想法：

1. 将放电标签和SSL分别对应条形图和折线图，使读者直观地知道哪一个属于哪一个。但ggplot2不允许我这样做，因为它会将两个轴的颜色都涂成相同的颜色。
2. 建立一个传说，清楚地表明红线属于SSL，蓝框图属于放电。有一个帖子here做了类似的事情，但我似乎无法实现它。如果有人可以帮助我，我将不胜感激。

这就是我的图表现在的样子。

这是我的脚本：

library(ggplot2)
library(gridExtra)
library(RColorBrewer)
library(tibble)

P_Discharge <- Pyay$Mean.monthly.discharge
P_MaxTemp <- Pyay$Mean.monthly.max.temperature
P_MinTemp <- Pyay$Mean.monthly.minimum.temperature
P_Rain <- Pyay$Max.monthly.rainfall
P_SSL <- Pyay$Mean.suspended.sediment.load

#reorderingthemonths
Pyay$Month <- factor(Pyay$Month, 
                     levels=c("Jan", "Feb", "Mar", "Apr", "May", "Jun", 
                              "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"))
#PlottingdischargeandSSL
Pgraph1 <- ggplot(Pyay, aes(x=Month, group=2))
Pgraph1 <- Pgraph1 + geom_bar(aes(y=P_Discharge), stat="identity", fill="blue")
Pgraph1 <- Pgraph1 + geom_line(aes(y=P_SSL), colour="red", size=1) +
  labs(y=expression(Q/(m^{3}))) +
  labs(x="")

#addingsecondaxis
Pgraph1 <- Pgraph1 + scale_y_continuous(sec.axis=sec_axis(~., name=expression(
  Suspended~sediment~load~(10^{6}~t))))

#colouringaxistitles
Pgraph1 <- Pgraph1 + theme(axis.title.x=element_blank(), 
                           axis.title.y=element_text(size=14), 
                           axis.text.x=element_text(size=14))

Pgraph1

数据

Pyay <- tibble::tribble(
              ~Month, ~Mean.monthly.discharge, ~Mean.monthly.max.temperature, ~Mean.suspended.sediment.load, ~Max.monthly.rainfall, ~Mean.monthly.minimum.temperature,
               "Jan",                   8.528,                          32.2,                         3.407,                   1.5,                              16.2,
               "Feb",                   6.316,                          35.1,                         2.319,                   0.9,                              17.8,
               "Mar",                       7,                          37.6,                         2.587,                   5.1,                              21.2,
               "Apr",                   8.635,                          38.7,                         3.573,                  27.3,                              24.7,
               "May",                  12.184,                            36,                         5.785,                 145.1,                              25.6,
               "Jun",                  30.414,                          31.9,                        21.811,                 234.8,                              24.8,
               "Jul",                  70.753,                            31,                        70.175,                   198,                              24.8,
               "Aug",                  79.255,                            31,                        81.873,                 227.5,                              24.7,
               "Sep",                  67.079,                          32.3,                        65.798,                 205.7,                              24.6,
               "Oct",                  53.677,                          33.5,                        47.404,                   124,                              24.2,
               "Nov",                  22.937,                          32.7,                        14.468,                    56,                              21.7,
               "Dec",                  12.409,                          31.5,                         5.842,                   1.5,                              18.1
              )

Answer 1

如果你把color和fill参数放在aes()里，你会得到一个传奇。使用scale_fill_manual，我们将条形图更改为蓝色。将color和fill labs()设置为""将它们移除。

##  Plotting discharge and SSL
Pgraph1 <- ggplot(Pyay, aes(x=Month, group = 2))
Pgraph1 <- Pgraph1 + geom_bar(aes(y=P_Discharge, fill = "discharge"), stat="identity")
Pgraph1 <- Pgraph1 + geom_line(aes(y=P_SSL, colour = "SSL"), size=1)+ labs(y=expression(Q/(m^{3}))) + labs(x=" ") 
Pgraph1 <- Pgraph1 + scale_fill_manual(values = c("discharge" = "blue")) + labs(color = "", fill = "")

#adding second axis 
Pgraph1 <- Pgraph1 + scale_y_continuous(sec.axis = sec_axis(~.,name = expression(Suspended~sediment~load~(10^{6}~t))))

#colouring axis titles
Pgraph1 <- Pgraph1 + theme(
  axis.title.x = element_blank(),
  axis.title.y = element_text(size=14),
  axis.text.x = element_text(size=14)
)
Pgraph1

Answer 2

您还可以考虑基本R图，我发现它更简单一些。

par(mar=c(5, 5, 4, 5) + 0.1)                                   # adjust plot margins
b <- barplot(Pyay$Mean.monthly.discharge, col="blue",          # plots and saves x-coordinates
             ylim=c(0, 90),
             ylab=expression(Q/(m^{3})))
lines(b, Pyay$Mean.suspended.sediment.load, col="red", lwd=2)  # use x-coordinates here
axis(1, b, labels=Pyay$Month)
axis(4, seq(0, 90, 20), labels=, seq(0, 90, 20))
mtext(expression(Suspended~sediment~load~(10^{6}~t)), 4, 3)
legend("topleft", legend=c("discharge", "SSL"), pch=c(15, NA),
       pt.cex=2, lty=c(0, 1), col=c("blue", "red"))
box()

给

---

数据

Pyay <- structure(list(Month = c("Jan", "Feb", "Mar", "Apr", "May", "Jun", 
"Jul", "Aug", "Sep", "Oct", "Nov", "Dec"), Mean.monthly.discharge = c(8.528, 
6.316, 7, 8.635, 12.184, 30.414, 70.753, 79.255, 67.079, 53.677, 
22.937, 12.409), Mean.monthly.max.temperature = c(32.2, 35.1, 
37.6, 38.7, 36, 31.9, 31, 31, 32.3, 33.5, 32.7, 31.5), Mean.suspended.sediment.load = c(3.407, 
2.319, 2.587, 3.573, 5.785, 21.811, 70.175, 81.873, 65.798, 47.404, 
14.468, 5.842), Max.monthly.rainfall = c(1.5, 0.9, 5.1, 27.3, 
145.1, 234.8, 198, 227.5, 205.7, 124, 56, 1.5), Mean.monthly.minimum.temperature = c(16.2, 
17.8, 21.2, 24.7, 25.6, 24.8, 24.8, 24.7, 24.6, 24.2, 21.7, 18.1
)), row.names = c(NA, -12L), class = "data.frame")