如何手动向ggplot对象添加图例

您可以通过使用熔化(在整形包中)轻松实现这一点。下面是定义数据帧后添加的代码。

id1 = c("month_num","founded_month", "founded_year","month_abb","short_year","label");   
m_summary3 = melt(m_summary2, id = id1);
p = ggplot(m_summary3, aes(x = month_num, y = value, group = variable, colour = variable));
c1 = rgb(0/255, 172/255, 0/255);
c2 = rgb(18/255, 111/255, 150/255);
x_scale = scale_x_continuous("Month", breaks = m_summary2$month_num, labels = m_summary2$label);
y_scale = scale_y_continuous("# Startups Founded")

p + geom_line() + scale_colour_manual(values = c(c1,c2)) + x_scale + y_scale;

拉姆纳特

这里有一种手动注释绘图的方法。我假设您保存了打印为p2的绘图。因此,您需要将此代码添加到您已有的代码中。

 x1 = max(m_summary2$month_num)-3;
 y1 = m_summary2$count[x1];
 y2 = m_summary2$proj[x1];
 a1 = annotate("text", x = x1, y = y1, label = "Current", vjust = -2, hjust = 0.2, colour = c1);
 a2 = annotate("text", x = x1, y = y2, label = "Projection", vjust = -2, hjust = 0.2, colour = c2);       
 p2 + a1 + a2;

让我知道这是否有效!

这是手动添加图例的另一种方法。这允许您选择属于每个图例名称的颜色,并可用作模板。这是一个明确的传说。

x <- 1:10
y <- x^2
z <- x^3
values = data.frame(x, y, z)
# Color has to be inside the aesthetic. 
ggplot(values, aes(x=x)) + 
geom_line(aes(y=y, 
              color="x^2")) + 
geom_line(aes(y=z, 
              color="x^3")) + 
scale_color_manual(name="", 
                   values=c("x^2"="cornflowerblue", "x^3"="lightgreen"))

这是定义颜色变量的更好方法。在可视化之前整理数据。这是一个含蓄的传说。

library(tidyverse)

sp500 = rnorm(10, 2400, 50)
nasdaq = rnorm(10, 6250, 100)
date = seq(Sys.Date(), Sys.Date()+9, 1)

dataMatrix = tibble(sp500, nasdaq, date)

dataMatrix %>% 
  # This creates a varaible for the indexes, which is used for coloring the lines. 
  gather(sp500, nasdaq, key="index", value="price") %>% 
    ggplot(aes(x=date, 
               y=price, 
               color=index)) +  
    geom_line() + 
  # This is used for customizing the legend. 
    scale_color_manual(
         name="Index",                   
         values=c("blue", "red"), 
         labels=c("Nasdaq", "S&P 500")) + 
  # This is used for customizing the plot descriptions. 
    labs(title="FINANCIAL MARKETS", 
         subtitle="USA INDEXES", 
         caption="MJR", 
         x="Date", 
         y="Price")