ggplot2包|散点图
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朋友们，实际工作中，你们用散点图吗？散点图一般用来做什么？散点图的变体有哪些？请大家留言。
本文介绍ggplot2包绘制散点图，一种基本的散点图，用于表示两个连续变量之间的关系。通过这种可视图，直观感受两变量之间会潜藏一种什么关系，为后续的分析和建模提供指导。利用ggplot2包绘制散点图，步骤如下：
首先，R包管理
if (!require("pacman")) {install.packages("pacman")require("pacman")}p_load(ggplot2, ggthemes, dplyr, scales, grid, showtext)
其次，数据获取和整理
采用R语言自带的airquality数据集。
data(airquality)glimpse(airquality)summary(airquality)
第三，逐步绘制散点图
1）基础的散点图
使用geom_point()函数
aq_trim <- airquality %>%filter(Month %in% c(7,8,9)) %>%mutate(Month = factor(Month,labels = c("July", "August", "September")))p1 <- ggplot(aq_trim, aes(x = Day, y = Ozone)) +geom_point()p1
2）修改点的形状
使用shape参数
p2 <- ggplot(aq_trim, aes(x = Day, y = Ozone)) +geom_point(shape = 21)p2
3）调整x轴的刻度
使用scale_x_continuous()函数
p3 <- p2 +scale_x_continuous(breaks = seq(1, 31, 5))p3
4）调整轴的标签和标题
使用labs()函数
p4 <- p3 +labs(title = "Air Quality in New York by Day") +labs(x = "Day of the month", y = "Ozone (ppb)")p4
5）配置调色板
p5 <- ggplot(aq_trim, aes(x = Day, y = Ozone)) +geom_point(shape = 21, colour = "mediumvioletred", fill = "springgreen") +labs(title = "Air Quality in New York by Day",subtitle = "Source: New York State Department of Conservation") +labs(x = "Day of the month", y = "Ozone (ppb)") +scale_x_continuous(breaks = seq(1, 31, 5))p5
或者
p5 <- ggplot(aq_trim, aes(x = Day, y = Ozone, fill = Month)) +geom_point(shape = 21) +labs(title = "Air Quality in New York by Day",subtitle = "Source: New York State Department of Conservation") +labs(x = "Day of the month", y = "Ozone (ppb)") +scale_x_continuous(breaks = seq(1, 31, 5))p5fill <- c("steelblue", "yellowgreen", "violetred1")p5 <- p5 + scale_fill_manual(values = fill)p5
6）图例管理
p6 <- p5 + theme(legend.position = "bottom",legend.direction = "horizontal")p6
7）字体设置
font_add("Tahoma","Tahoma.ttf")showtext_auto()
8）配置主题风格
a) 使用经济学杂志主题
p8_1 <- ggplot(aq_trim, aes(x = Day, y = Ozone, fill = Month)) +geom_point(shape = 21) +labs(title = "Air Quality in New York by Day",subtitle = "Source: New York State Department of Conservation") +labs(x = "Day of the month", y = "Ozone (ppb)", fill = "Months ") +scale_x_continuous(breaks = seq(1, 31, 5)) +scale_size(range = c(1, 10)) +theme_economist() + scale_fill_economist() +theme(axis.line.x = element_line(size = .5, colour = "black"),axis.title = element_text(size = 12),legend.position = "bottom", legend.direction = "horizontal",legend.text = element_text(size = 10),plot.title = element_text(family = "Tahoma"),text = element_text(family = "Tahoma"))p8_1
b) 使用自定义主题
fill <- c("#56B4E9","#F0E442","violetred1")p8_2 <- ggplot(aq_trim, aes(x = Day, y = Ozone, fill = Month)) +geom_point(shape = 21) +labs(title = "Air Quality in New York by Day",subtitle = "Source: New York State Department of Conservation") +labs(x = "Day of the month", y = "Ozone (ppb)", fill = "Months ") +scale_x_continuous(breaks = seq(1, 31, 5)) +scale_fill_manual(values = fill) +scale_size(range = c(1, 10)) +theme(axis.line.x = element_line(size = .5, colour = "black"),axis.line.y = element_line(size = .5, colour = "black"),axis.text.x = element_text(colour = "black", size = 10),axis.text.y = element_text(colour = "black", size = 10),legend.position = "bottom",legend.direction = "horizontal",legend.key = element_blank(),panel.grid.major = element_blank(),panel.grid.minor = element_blank(),panel.background = element_blank(),plot.title = element_text(family = "Tahoma"),text = element_text(family = "Tahoma"))p8_2
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附录：完整代码
##################散点图#2021-03-21################## 1 R包管理if (!require("pacman")) {install.packages("pacman")require("pacman")}p_load(ggplot2, ggthemes, dplyr, scales, grid, showtext)# 2 数据获取和理解data(airquality)glimpse(airquality)summary(airquality)# 3 逐步画散点图# 1）基础散点图# 选择需要绘制图形的数据集aq_trim <- airquality %>%filter(Month %in% c(7,8,9)) %>%mutate(Month = factor(Month,labels = c("July", "August", "September")))p1 <- ggplot(aq_trim, aes(x = Day, y = Ozone)) +geom_point()p1# 2）修改点的形状p2 <- ggplot(aq_trim, aes(x = Day, y = Ozone)) +geom_point(shape = 21)p2# 3）调整x周的刻度p3 <- p2 +scale_x_continuous(breaks = seq(1, 31, 5))p3# 4）调整轴标签和标题p4 <- p3 +labs(title = "Air Quality in New York by Day") +labs(x = "Day of the month", y = "Ozone (ppb)")p4# 5）调整调色板p5 <- ggplot(aq_trim, aes(x = Day, y = Ozone)) +geom_point(shape = 21, colour = "mediumvioletred", fill = "springgreen") +labs(title = "Air Quality in New York by Day",subtitle = "Source: New York State Department of Conservation") +labs(x = "Day of the month", y = "Ozone (ppb)") +scale_x_continuous(breaks = seq(1, 31, 5))p5# 或者p5 <- ggplot(aq_trim, aes(x = Day, y = Ozone)) +geom_point(shape = 21, colour = "#000000", fill = "#40b8d0") +labs(title = "Air Quality in New York by Day",subtitle = "Source: New York State Department of Conservation") +labs(x = "Day of the month", y = "Ozone (ppb)") +scale_x_continuous(breaks = seq(1, 31, 5))p5# 或者p5 <- ggplot(aq_trim, aes(x = Day, y = Ozone, fill = Month)) +geom_point(shape = 21) +labs(title = "Air Quality in New York by Day",subtitle = "Source: New York State Department of Conservation") +labs(x = "Day of the month", y = "Ozone (ppb)") +scale_x_continuous(breaks = seq(1, 31, 5))p5fill <- c("steelblue", "yellowgreen", "violetred1")p5 <- p5 + scale_fill_manual(values = fill)p5# 6）图例管理p6 <- p5 + theme(legend.position = "bottom",legend.direction = "horizontal")p6# 7) 字体设置font_add("Tahoma","Tahoma.ttf")showtext_auto()# 8）配置主题风格# 8.1）使用经济学杂志主题p8_1 <- ggplot(aq_trim, aes(x = Day, y = Ozone, fill = Month)) +geom_point(shape = 21) +labs(title = "Air Quality in New York by Day",subtitle = "Source: New York State Department of Conservation") +labs(x = "Day of the month", y = "Ozone (ppb)", fill = "Months ") +scale_x_continuous(breaks = seq(1, 31, 5)) +scale_size(range = c(1, 10)) +theme_economist() + scale_fill_economist() +theme(axis.line.x = element_line(size = .5, colour = "black"),axis.title = element_text(size = 12),legend.position = "bottom", legend.direction = "horizontal",legend.text = element_text(size = 10),plot.title = element_text(family = "Tahoma"),text = element_text(family = "Tahoma"))p8_1# 2) 自定义主题fill <- c("#56B4E9","#F0E442","violetred1")p8_2 <- ggplot(aq_trim, aes(x = Day, y = Ozone, fill = Month)) +geom_point(shape = 21) +labs(title = "Air Quality in New York by Day",subtitle = "Source: New York State Department of Conservation") +labs(x = "Day of the month", y = "Ozone (ppb)", fill = "Months ") +scale_x_continuous(breaks = seq(1, 31, 5)) +scale_fill_manual(values = fill) +scale_size(range = c(1, 10)) +theme(axis.line.x = element_line(size = .5, colour = "black"),axis.line.y = element_line(size = .5, colour = "black"),axis.text.x = element_text(colour = "black", size = 10),axis.text.y = element_text(colour = "black", size = 10),legend.position = "bottom",legend.direction = "horizontal",legend.key = element_blank(),panel.grid.major = element_blank(),panel.grid.minor = element_blank(),panel.background = element_blank(),plot.title = element_text(family = "Tahoma"),text = element_text(family = "Tahoma"))p8_2
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