如何使用 ggplot 在 r 中绘制多行图

问题描述：

我正在尝试使用 ggplot 在 r 中绘制 3 行图形，但第三行没有出现在图形中.我使用了以下代码:

I am trying to do a graph in r with 3 lines using ggplot, but the third line does not appear in the graph. I used the following code:

us_idlpnts <- subset(unvoting, CountryName == "United States of America")
rus_idlpnts <- subset(unvoting, CountryName == "Russia")

mdn_idl_pnt <- summarize(unvoting, PctAgreeUS = median(PctAgreeUS, na.rm=T), PctAgreeRUSSIA = median(PctAgreeRUSSIA, na.rm=T), idealpoint = median(idealpoint, na.rm=T), Year = median(Year, na.rm= T))

ggplot(NULL, aes(Year, idealpoint)) + geom_line(data = us_idlpnts, col = "blue") + geom_line(data = rus_idlpnts, col = "red") + geom_line(data = mdn_idl_pnt , col = "green") + ggtitle("Ideal Points of US and Russia") + labs(y = "Ideal Points", x = "Year", color = "legend") + scale_color_manual(values= colors)

答

让我们按原样考虑您的情节:

Let's consider your plot as is:

library(ggplot2)
library(qss)
data(unvoting)
us_idlpnts <- subset(unvoting, CountryName == "United States of America")
rus_idlpnts <- subset(unvoting, CountryName == "Russia")
mdn_idl_pnt <- summarize(unvoting, PctAgreeUS = median(PctAgreeUS, na.rm=T),
                         PctAgreeRUSSIA = median(PctAgreeRUSSIA, na.rm=T),
                         idealpoint = median(idealpoint, na.rm=T),
                         Year = median(Year, na.rm= T))
ggplot(NULL, aes(Year, idealpoint)) +
  geom_line(data = us_idlpnts, col = "blue") +
  geom_line(data = rus_idlpnts, col = "red") +
  geom_line(data = mdn_idl_pnt , col = "green") +
  ggtitle("Ideal Points of US and Russia") +
  labs(y = "Ideal Points", x = "Year", color = "legend") +
  scale_color_manual(values= colors)

如果我们检查mdn_idl_pnt，第三行没有绘制的原因就会很明显.

The reason the third line does not plot will become obvious if we inspect mdn_idl_pnt.

mdn_idl_pnt
#  PctAgreeUS PctAgreeRUSSIA idealpoint Year
#1       0.24      0.6567164 -0.1643651 1987

在您的 ggplot 调用中，您映射 x = Year 和 y = Idealpoint.然而，每个Year 和idealpoint 只有一个值.不能从一个点创建一条线.

In your ggplot call, you map x = Year and y = idealpoint. Yet there is only one value of each Year and idealpoint. A line cannot be created from a single point.

也许你想添加一个 geom_hline?

ggplot(NULL, aes(Year, idealpoint)) +
  geom_line(data = us_idlpnts, col = "blue") +
  geom_line(data = rus_idlpnts, col = "red") +
  geom_hline(yintercept = mdn_idl_pnt$idealpoint, col = "green") +
  ggtitle("Ideal Points of US and Russia") +
  labs(y = "Ideal Points", x = "Year", color = "legend") +
  scale_color_manual(values= colors)

如何使用 ggplot 在 r 中绘制多行图

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