生成绘图数据
set.seed(1234)
dat <- data.frame(cond = factor(rep(c("A","B"), each=200)),
rating = c(rnorm(200),rnorm(200, mean=.8)))
# View first few rows
head(dat)
直方图和概率密度图
## Basic histogram from the vector "rating". Each bin is .5 wide.
## These both result in the same output:
ggplot(dat, aes(x=rating)) + geom_histogram(binwidth=.5) # rating作为横轴
image.png
#
ggplot(dat, aes(x=rating)) +
geom_histogram(binwidth=.5,
colour="black", # 边框颜色
fill="white" #填充颜色
)
image.png
ggplot(dat, aes(x=rating)) + geom_density() # 添加密度曲线
image.png
# Histogram overlaid with kernel density curve
ggplot(dat, aes(x=rating)) +
geom_histogram(aes(y=..density..), # 这一步很重要,使用density代替y轴
binwidth=.5,
colour="black", fill="white") +
geom_density(alpha=.2, fill="#FF6666") # 重叠部分采用透明设置
image.png
添加一条均值线(红色部分)
ggplot(dat, aes(x=rating)) +
geom_histogram(binwidth=.5, colour="black", fill="white") +
geom_vline(aes(xintercept=mean(rating, na.rm=T)), # Ignore NA values for mean
color="red", linetype="dashed", size=1)
image.png
多组数据的直方图和密度图
# cond作为各组的分类,以颜色填充作为区别
# position的处理很重要,决定数据存在重叠是的处理方式 "identity" 不做处理,但是设置了透明
ggplot(dat, aes(x=rating, fill=cond)) +
geom_histogram(binwidth=.5, alpha=.5, position="identity")
image.png
# Interleaved histograms
ggplot(dat, aes(x=rating, fill=cond)) +
geom_histogram(binwidth=.5, position="dodge")
image.png
# dodge 表示重叠部分进行偏离
# 密度图
ggplot(dat, aes(x=rating, colour=cond)) + geom_density()
image.png
# 半透明的填充
ggplot(dat, aes(x=rating, fill=cond)) + geom_density(alpha=.3)
image.png
# Find the mean of each group
library(plyr)
# 以 cond 作为分组, 计算每组的rating的均值
cdat <- ddply(dat, "cond", summarise, rating.mean=mean(rating))
cdat
# 绘制两组数据的均值
ggplot(dat, aes(x=rating, fill=cond)) +
geom_histogram(binwidth=.5, alpha=.5, position="identity") +
geom_vline(data=cdat, aes(xintercept=rating.mean, colour=cond),
linetype="dashed", size=1)
image.png
密度图
ggplot(dat, aes(x=rating, colour=cond)) +
geom_density() +
geom_vline(data=cdat, aes(xintercept=rating.mean, colour=cond),
linetype="dashed", size=1)
image.png
使用分面
# 按照 cond 进行分面处理, 上图为A,下图为B
ggplot(dat, aes(x=rating)) + geom_histogram(binwidth=.5, colour="black", fill="white") +
facet_grid(cond ~ .)
image.png
# 添加均值线
ggplot(dat, aes(x=rating)) + geom_histogram(binwidth=.5, colour="black", fill="white") +
facet_grid(cond ~ .) +
geom_vline(data=cdat, aes(xintercept=rating.mean),
linetype="dashed", size=1, colour="red")
image.png
