ggplot2 003 绘图参数 — 标题及图例

ggplot2 Graphical Parameters

• Main title, axis labels and legend title
• Legend position and appearance
• Change colors automatically and manually
• Point shapes, colors and size
• Add text annotations to a graph
• Line types
• Themes and background colors
• Axis scales and transformations
• Axis ticks: customize tick marks and labels, reorder and select items
• Add straight lines to a plot: horizontal, vertical and regression lines
• Rotate a plot: flip and reverse
• Faceting: split a plot into a matrix of panels

1.标题：主标题，轴和图例标题

ggplot2软件包修改绘图标题（主标题，轴标签和图例标题）主要是通过以下函数：

• ggtitle（label）＃主标题
• xlab（label）＃x轴标签
• ylab（label）＃y轴标签
• labs（...）＃用于主标题，轴标签和图例标题

1.1 数据准备

# 将dose转换weight因子
ToothGrowth$dose <- as.factor(ToothGrowth$dose)
# 检查数据
head(ToothGrowth)
library(ggplot2)
p <- ggplot(ToothGrowth, aes(x=dose, y=len)) + geom_boxplot()
p

image.png

1.2 更改主标题及轴标题

1.2.1 使用 ggtitle(), xlab() and ylab()

p + ggtitle("Plot of length \n by dose") +
  xlab("Dose (mg)") + ylab("Teeth length")

image.png

1.2.2 使用labs()

p +labs(title="Plot of length \n by dose",
        x ="Dose (mg)", y = "Teeth length")

image.png

1.3 使用labs()更改图例

p <- ggplot(ToothGrowth, aes(x=dose, y=len, fill=dose))+
  geom_boxplot()
p
# 更改图例
p1 <- p + labs(fill = "Dose (mg)")

image.png

1.4 更改主标题和轴标签的外观

可以使用theme()和element_text()函数自定义主标题以及x和y轴标签

# main title
p + theme(plot.title = element_text(family, face, colour, size))
# x axis title 
p + theme(axis.title.x = element_text(family, face, colour, size))
# y axis title
p + theme(axis.title.y = element_text(family, face, colour, size))

## family : font family
## face : font face. Possible values are “plain”, “italic”, “bold” and “bold.italic”
## colour : text color
## size : text size in pts
## hjust : horizontal justification (in [0, 1])
## vjust : vertical justification (in [0, 1])
## lineheight : line height. In multi-line text, the lineheight argument is used to change the
## spacing between lines.
## color : an alias for colour

• example

# Default plot
p <- ggplot(ToothGrowth, aes(x=dose, y=len)) + geom_boxplot() +
  ggtitle("Plot of length \n by dose") +
  xlab("Dose (mg)") + ylab("Teeth length")
p
# Change the color, the size and the face of
# the main title, x and y axis labels
p1 <- p + theme(
plot.title = element_text(color="red", size=14, face="bold.italic"),
axis.title.x = element_text(color="blue", size=14, face="bold"),
axis.title.y = element_text(color="#993333", size=14, face="bold")
)
ggarrange(p,p1)

image.png

1.5 移除x和y轴标签

可以使用element_blank()函数隐藏主要标题和轴标签

p + theme(
  plot.title = element_blank(),
  axis.title.x = element_blank(),
  axis.title.y = element_blank())

image.png

2 图例的位置及外观

2.1 数据准备

# 将dose转换weight因子
ToothGrowth$dose <- as.factor(ToothGrowth$dose)
# 检查数据
head(ToothGrowth)
library(ggplot2)
p <- ggplot(ToothGrowth, aes(x=dose, y=len, fill=dose)) + 
  geom_boxplot()
p

image.png

2.2 更改图例位置

可以使用theme()函数来更改图例的位置

# legend.position are : “left”,“top”, “right”, “bottom”,vector c(x,y)
p1 <- p + theme(legend.position="top")
p2 <- p + theme(legend.position="bottom")
p3 <- p + theme(legend.position = c(0.8, 0.2))
ggarrange(p1,p2,p3,nrow=1)

image.png

2.3 更改图例标题和文本字体样式

# 图例标题
p4 <- p + theme(legend.title = element_text(colour="blue", size=10, 
                                      face="bold"))
# 图例标签
p5 <- p + theme(legend.text = element_text(colour="blue", size=10, 
                                     face="bold"))
ggarrange(p4,p5)

image.png

2.4 更改图例框的背景颜色

# 背景颜色修改
p6 <- p + theme(legend.background = element_rect(fill="lightblue", 
                                           size=0.5, linetype="solid"))
p7 <- p + theme(legend.background = element_rect(fill="lightblue",
                                           size=0.5, linetype="solid", 
                                           colour ="darkblue"))
ggarrange(p6,p7)

image.png

2.5 更改图例项的顺序

p + scale_x_discrete(limits=c("2", "0.5", "1"))

image.png

2.6 移除图例

# Remove only the legend title
p8 <- p + theme(legend.title = element_blank())
# Remove the plot legend
p9 <- p + theme(legend.position='none')
ggarrange(p8,p9)

image.png

2.7 删除条形图例中的斜线

# 默认图
p10 <- ggplot(data=ToothGrowth, aes(x=dose, fill=dose)) + geom_bar()
# 更改条形图边框颜色，
# 但在图例中添加了斜杠
p11 <- ggplot(data=ToothGrowth, aes(x=dose, fill=dose)) +
  geom_bar(colour="black")
p11
# 隐藏斜线：
# 1.绘制没有边框颜色的条，
# 2.再次用边框颜色绘制条形，但带有空白图例。
p12 <- ggplot(data=ToothGrowth, aes(x=dose, fill=dose))+ 
  geom_bar() + 
  geom_bar(colour="black", show.legend = FALSE)
ggarrange(p10,p11,p12,nrow = 1)

然而很尴尬，第二幅图的图例并没有出现斜线

image.png

3. guides() 设置或删除图例以获得特定的美感

3.1 设置或删除具有特定美感的图例（填充，颜色，大小，形状等）

# Prepare the data : convert cyl and gear to factor variables
mtcars$cyl<-as.factor(mtcars$cyl)
mtcars$gear <- as.factor(mtcars$gear)
head(mtcars)
p <- ggplot(data = mtcars, 
            aes(x=mpg, y=wt, color=cyl, size=qsec, shape=gear))+
  geom_point()
# Print the plot without guide specification
p

image.png

3.2 更改多个指南的图例位置

# Change the legend position
p +theme(legend.position="bottom")

image.png

# Horizontal legend box
p +theme(legend.position="bottom", legend.box = "horizontal")

image.png

3.3 更改多个图例的顺序

p+guides(color = guide_legend(order=1),
         size = guide_legend(order=2),
         shape = guide_legend(order=3))

image.png

如果使用连续颜色，则可以使用功能guide_colourbar()更改颜色指南的顺序：

qplot(data = mpg, x = displ, y = cty, size = hwy,
      colour = cyl, shape = drv) +
  guides(colour = guide_colourbar(order = 1),
         alpha = guide_legend(order = 2),
         size = guide_legend(order = 3))

image.png

3.4 删除具有特殊美感的图例

p+guides(color = FALSE, size = FALSE)

image.png

# Remove legend for the point shape
p1 <- p+scale_shape(guide=FALSE)
# Remove legend for size
p2 <- p +scale_size(guide=FALSE)
# Remove legend for color
p3 <- p + scale_color_manual(values=c('#999999','#E69F00','#56B4E9'),
                       guide=FALSE)
ggarrange(p1,p2,p3,nrow = 1)

image.png