ggplot2学习笔记

下载我们使用的数据

library(ggplot2)
X <- read.delim("http://www.stat.ubc.ca/~rickw/gapminderDataFiveYear.txt")
str(X)

## 'data.frame':    1704 obs. of  6 variables:
##  $ country  : Factor w/ 142 levels "Afghanistan",..: 1 1 1 1 1 1 1 1 1 1 ...
##  $ year     : int  1952 1957 1962 1967 1972 1977 1982 1987 1992 1997 ...
##  $ pop      : num  8425333 9240934 10267083 11537966 13079460 ...
##  $ continent: Factor w/ 5 levels "Africa","Americas",..: 3 3 3 3 3 3 3 3 3 3 ...
##  $ lifeExp  : num  28.8 30.3 32 34 36.1 ...
##  $ gdpPercap: num  779 821 853 836 740 ...

qplot基本用法

qplot最简单的使用方法和R base中的plot基本一样可以用来画散点图

library(ggplot2)
X <- read.delim("http://www.stat.ubc.ca/~rickw/gapminderDataFiveYear.txt")
qplot(gdpPercap, lifeExp, data=X)

使用 color = year 可以将该变量用不同颜色标示出来, 这里year是个连续的变量所以颜色以谱的形式标示, 用 log = "x" 表示对横轴的变量进行log变换

library(ggplot2)
X <- read.delim("http://www.stat.ubc.ca/~rickw/gapminderDataFiveYear.txt")
qplot(gdpPercap, lifeExp, data=X, log = "x", color = year)

也可以将year变成factor,此时会用离散的颜色标示

library(ggplot2)
X <- read.delim("http://www.stat.ubc.ca/~rickw/gapminderDataFiveYear.txt")
qplot(gdpPercap, lifeExp, data=X, log = "x", color = factor(year))

使用 size = pop 用标志的大小显示该变量的大小

library(ggplot2)
X <- read.delim("http://www.stat.ubc.ca/~rickw/gapminderDataFiveYear.txt")
qplot(gdpPercap, lifeExp, data=X, log = "x", color = year, size = pop)

还可以使用 shape = continent 用不同的标志来显示该变量

library(ggplot2)
X <- read.delim("http://www.stat.ubc.ca/~rickw/gapminderDataFiveYear.txt")
qplot(gdpPercap, lifeExp, data=X, log = "x", color = year, shape = continent)

最后 alpha=I(0.25) 指定透明度 0为全透明 1为不透明当数据重叠严重时比较有用

library(ggplot2)
X <- read.delim("http://www.stat.ubc.ca/~rickw/gapminderDataFiveYear.txt")
qplot(gdpPercap, lifeExp, data=X, log = "x", alpha=I(0.25))

geom

geom是geometric object的简称用来生成不同种类的图

smooth

首先是smooth 用来描述数据的平滑趋势注意此处 c(“point”, “smooth”) 表示先画point 再画smooth

library(ggplot2)
X <- read.delim("http://www.stat.ubc.ca/~rickw/gapminderDataFiveYear.txt")
qplot(gdpPercap, lifeExp, data=X, log = "x", alpha=I(0.5), geom=c("point", "smooth"))

## `geom_smooth()` using method = 'gam'

相反的 c(“smooth”, “point”) 就是先画smooth 再画point

library(ggplot2)
X <- read.delim("http://www.stat.ubc.ca/~rickw/gapminderDataFiveYear.txt")
qplot(gdpPercap, lifeExp, data=X, log = "x", alpha=I(0.5), geom=c("smooth", "point"))

## `geom_smooth()` using method = 'gam'

除了默认的平滑方法之外,还可以自行指定,比如线性模型

library(ggplot2)
X <- read.delim("http://www.stat.ubc.ca/~rickw/gapminderDataFiveYear.txt")
qplot(gdpPercap, lifeExp, data=X, log = "x", alpha=I(0.5), geom=c("point", "smooth"), method=lm)

## Warning: Ignoring unknown parameters: method

另外还可以自行指定公式例如多项式回归

library(ggplot2)
X <- read.delim("http://www.stat.ubc.ca/~rickw/gapminderDataFiveYear.txt")
qplot(gdpPercap, lifeExp, data=X, log = "x", alpha=I(0.5), geom=c("point", "smooth"), method=lm, formula = y ~ poly(x, 3))

## Warning: Ignoring unknown parameters: method, formula

line和path

line会将数据沿横轴方向按顺序连接起来一般用来表示时间序列数据

library(ggplot2)
X <- read.delim("http://www.stat.ubc.ca/~rickw/gapminderDataFiveYear.txt")
qplot(pop, lifeExp, data=X, log = "x", alpha=I(0.5), color=year, geom="line")

path会将原始数据中相邻的两个点连接起来一般用来表示二维数据随时间的变化

library(ggplot2)
X <- read.delim("http://www.stat.ubc.ca/~rickw/gapminderDataFiveYear.txt")
qplot(gdpPercap, lifeExp, data=X, log = "x", alpha=I(0.5), color=year, geom=c("point", "path"))

=====

boxplot和jitter

和R base中的boxplot一样,横轴的数据需要是factor

注意 color=I(“red”) 中的I()是必须的否则“red”会被当做一个新的factor

library(ggplot2)
X <- read.delim("http://www.stat.ubc.ca/~rickw/gapminderDataFiveYear.txt")
X$year.fac <- factor(X$year)
qplot(year.fac, lifeExp, data=X, color=I("red"), geom="boxplot")

jitter和boxplot类似

library(ggplot2)
X <- read.delim("http://www.stat.ubc.ca/~rickw/gapminderDataFiveYear.txt")
X$year.fac <- factor(X$year)
qplot(year.fac, lifeExp, data=X, color=I("red"), geom="jitter")

histogram和density

这里使用 fill=continent 将直方图按不同的continent分割开

library(ggplot2)
X <- read.delim("http://www.stat.ubc.ca/~rickw/gapminderDataFiveYear.txt")
qplot(lifeExp,data=X, geom="histogram", fill=continent)

## `stat_bin()` using `bins = 30`. Pick better value with `binwidth`.

density与histogram类似

library(ggplot2)
X <- read.delim("http://www.stat.ubc.ca/~rickw/gapminderDataFiveYear.txt")
qplot(lifeExp,data=X, alpha=I(0.5), geom="density", color=continent)

facets

使用facets可以将一个图根据一个或两个变量的值分别显示出来有利于更直观地进行比较 ~左边表示每一行的变量右边表示每一列的变量比如 continent~. 根据continent值的不同将density的图在每一行里显示出来

library(ggplot2)
X <- read.delim("http://www.stat.ubc.ca/~rickw/gapminderDataFiveYear.txt")
qplot(lifeExp,data=X, geom="density", facets=continent~.)

类似的 facets=year~continent 根据每一行year和每一列continent值的不同将histogram的图显示出来

library(ggplot2)
X <- read.delim("http://www.stat.ubc.ca/~rickw/gapminderDataFiveYear.txt")
qplot(lifeExp,data=X, geom="histogram", facets=year~continent)

## `stat_bin()` using `bins = 30`. Pick better value with `binwidth`.

ggplot2学习笔记

weiliangxiao

2017年2月26日