R ggplot2：标记水平线而不将标签与系列相关联 [英] R ggplot2: Labeling a horizontal line without associating the label with a series

问题描述

我想在一个ggplot 上标注一个水平线，并带有多个系列，而不需要将该线与一个系列相关联。

我如何标记行没有将标签与系列标签关联？

解决方案

这是您的想法吗？ b

<$ p $ （数据帧）（y = 1：10，x = 1：10，col = c（a，b））＃添加了col
h <-7.1
ggplot（df，aes（x = x，y = y））+
geom_point（aes（color = col））+
geom_hline yintercept = h）+
geom_text（data = data.frame（x = 0，y = h），aes（x，y），label = h，vjust = -1）

首先，您可以将颜色映射局部应用于点图层。其次，您不必将所有美学内容都放入对 aes（...）的调用中 - 只有那些您希望映射到数据集列中的美学。三，你可以在 data = ... 中调用特定的geom _ *。

来创建特定于图层的数据集

I'd like to label a horizontal line on a ggplot with multiple series, without associating the line with a series. R ggplot2: Labelling a horizontal line on the y axis with a numeric value asks about the single-series case, for which geom_text solves. However, geom_text associates the label with one of the series via color and legend.

Consider the same example from that question, with another color column:

library(ggplot2)
df <- data.frame(y=1:10, x=1:10, col=c("a", "b"))  # Added col
h <- 7.1
plot1 <- ggplot(df, aes(x=x, y=y, color=col)) + geom_point()
plot2 <- plot1 + geom_hline(aes(yintercept=h))
# Applying top answer https://stackoverflow.com/a/12876602/1840471
plot2 + geom_text(aes(0, h, label=h, vjust=-1))

How can I label the line without associating the label to one of the series?

解决方案

Is this what you had in mind?

library(ggplot2)
df <- data.frame(y=1:10, x=1:10, col=c("a", "b"))  # Added col
h <- 7.1
ggplot(df, aes(x=x,y=y)) + 
  geom_point(aes(color=col)) +
  geom_hline(yintercept=h) +
  geom_text(data=data.frame(x=0,y=h), aes(x, y), label=h, vjust=-1)

First, you can make the color mapping local to the points layer. Second, you do not have to put all the aesthetics into calls to aes(...) - only those you want mapped to columns of the dataset. Three, you can have layer-specific datasets using data=... in the calls to a specific geom_*.

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