为条形图和线条创建通用图例

Question

我对R非常陌生，因此如果这是一个非常基本的问题，我会提前道歉。

我正在尝试绘制一个显示出水和悬浮泥沙量（SSL）的图表。但是，我想弄清楚条形图表示放电，而线图表示SSL。我有两个想法：

1. 为放电标签和SSL分别上色以分别对​​应于条形图和折线图，因此读者可以直观地知道哪个标签属于哪个标签。但是ggplot2不允许我这样做，因为它将以相同的颜色为两个y轴着色。

2. 建立一个图例，清楚地表明红线属于SSL，蓝框图属于排放。有一个帖子在这里它做类似的事情，但我似乎无法实现它。如果有人可以帮助我，我将不胜感激。

这就是我现在的图。

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

如果您将color和fill参数放入其中，aes()您将得到一个图例。我们scale_fill_manual将条形更改为蓝色。设置color和fill labs()来""删除它们。

##  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