R编程中如何使用ggplot2包？用法示例指南

2021年4月3日17:05:45 发表评论 880 次浏览

ggplot2也被称为图形语法，它是一个免费的、开源的、易于使用的可视化包，广泛应用于R中。它是Hadley Wickham编写的功能最强大的可视化包。

它包括对其进行管理的几层。图层如下：

图层的构建块

具有感兴趣变量的层如下：

Aesthetics美学：x轴, y轴, 颜色, 填充, 大小, 标签, alpha, 形状, 线宽, 线型
Geometrics几何学：点, 线, 直方图, 条形图, 箱线图
Facets构面：列, 行
Statistics统计：分档, 平滑, 描述性, 中间
Coordinates坐标：笛卡尔, 固定, 极点, 极限
Themes主题：非数据链接

数据集

mtcars(汽车趋势汽车道路测试)包括油耗以及32辆汽车的10个方面的汽车设计和性能, 并预先安装了dplyr在R中打包。

# Installing the package
install.packages( "dplyr" )
  
# Loading package
library(dplyr)
  
# Summary of dataset in package
summary(mtcars)

在数据集上执行ggplot2

我们设计可视化mtcars包含32个汽车品牌和11个属性的数据集ggplot2层。

# Installing the package
install.packages( "ggplot2" )
   
# Loading packages
library(ggplot2)
library(dplyr)
   
# Data Layer
ggplot(data = mtcars)
   
# Aesthetic Layer
ggplot(data = mtcars, aes(x = hp, y = mpg, col = disp))
   
# Geometric layer
ggplot(data = mtcars, aes(x = hp, y = mpg, col = disp)) + geom_point()
   
# Adding size
ggplot(data = mtcars, aes(x = hp, y = mpg, size = disp)) + geom_point()
   
# Adding color and shape
ggplot(data = mtcars, aes(x = hp, y = mpg, col = factor(cyl), shape = factor(am))) + geom_point()
   
# Histogram plot
ggplot(data = mtcars, aes(x = hp)) +
        geom_histogram(binwidth = 5 )
   
# Facet Layer
p < - ggplot(data = mtcars, aes(x = hp, y = mpg, shape = factor(cyl))) + geom_point()
   
# Separate rows according to transmission type
p + facet_grid(am ~ .)
   
# Separate columns according to cylinders
p + facet_grid(. ~ cyl)
   
# Statistics layer
ggplot(data = mtcars, aes(x = hp, y = mpg)) + 
                                geom_point() + 
        stat_smooth(method = lm, col = "red" )
   
# Coordinates layer: Control plot dimensions
ggplot(data = mtcars, aes(x = wt, y = mpg)) +
                                geom_point() +
       stat_smooth(method = lm, col = "red" ) +
  scale_y_continuous( "mpg" , limits = c( 2 , 35 ), expand = c( 0 , 0 )) +
   scale_x_continuous( "wt" , limits = c( 0 , 25 ), expand = c( 0 , 0 )) + coord_equal()
   
# Add coord_cartesian() to proper zoom in
ggplot(data = mtcars, aes(x = wt, y = hp, col = am)) +
                         geom_point() + geom_smooth() +
                         coord_cartesian(xlim = c( 3 , 6 ))
   
# Theme layer
ggplot(data = mtcars, aes(x = hp, y = mpg)) +
          geom_point() + facet_grid(. ~ cyl) +
         theme(plot.background = element_rect(
             fill = "black" , colour = "gray" ))
   
ggplot(data = mtcars, aes(x = hp, y = mpg)) +
         geom_point() + facet_grid(am ~ cyl) + 
         theme_gray()

输出如下：

几何层