​圆环图与饼图类似，也是反映各个部分的占比情况，看各种类型的数据与整体之间的关系。下面将展示一下在R与python中的实现方法。

1. R的实现 (ggplot2)

R中是没有封装好的包来直接实现的，我们将用ggplot2中的geom_bar进行极坐标变换得到。首先创建两组数：

data1 <- data.frame("cell1" = c(30,25, 66, 13, 23)/sum(c(30,25, 66, 13, 23)), 'type' = c('Intron', 'Intergenic',"UTR","Exon","CDS"))
data2 <- data.frame("cell2" = c(29, 28, 90, 19, 31)/sum(c(29, 28, 90, 19, 31)), "type" = c('Intron', 'Intergenic',"UTR","Exon","CDS"))

Then draw the barplot of these two sets of numbers:

library(ggplot2)
theme_set(theme_bw())
p <- ggplot() + geom_bar(data1, mapping = aes(x = 0.8, y = cell1, fill = type), color = "gray", stat ='identity', width = 0.4) + geom_bar(data2, mapping = aes(x = 0.5, y = cell2, fill = type), color ='gray',width = 0.3, stat ='identity') + labs(y ='cells', y ='percentage')  
p

image

After the polar coordinate changes, we can get:

p + coord_polar(theta='y')

image

It still doesn't look good now, and finally remove the xy axis scale and the title of the xy axis:

p + theme(axis.title.x=element_blank(), axis.title.y=element_blank(), panel.border=element_blank(), panel.grid=element_blank(), axis.ticks = element_blank(), axis. text = element_blank()) + guides(fill = guide_legend(title ='type'))

image

2. Implementation of python (matplotlib.pyplot)

Python will use pyplot in matplotlib to draw two pie graphs to achieve.

import pandas as pd
import matplotlib.pyplot as plt
import matplotlib as mpl
mpl.rcParams['font.size'] = 7.0 # matplotlib sets the global font
​
# Create two sets of data
x1 = [30,25, 66, 13, 23]
x2 = [29, 28, 90, 19, 31]
​
x_0 = [1,0,0,0] #Used to display hollow
 
​Labels = ["Intron","Intergenic","UTR","Exon","CDS"] # Label
colors = ["#FFDD55","#EE7700","#99FF99","#5599FF","#FF77FF"] # Corresponding colors
​
# Used to set the font and size of the legend
font1 = {'family':'Times New Roman',
'weight':'normal',
'size': 10,
        }
# Create picture        
plt.figure(figsize=(8,8))
fig, ax = plt.subplots()
​
#Make three pie pictures, the last one is used as the hollow in the middle
pie_1 = ax.pie(x1,startangle = 90, radius=1.8, pctdistance = 0.9, colors=colors)
pie_2 = ax.pie(x2,startangle = 90,radius=1.5,pctdistance = 0.9,colors=colors)
pie_0 = ax.pie(x_0, radius=1.2,colors ='w')
​
# Set image title
ax.text(0.1, 2.1,'test', fontsize=18, style='oblique', ha='center',va='top',wrap=True)
​
# Draw the color of the edge of each pie graph
for pie_wedge in pie_1[0]:
    pie_wedge.set_edgecolor('gray')
for pie_wedge in pie_2[0]:
    pie_wedge.set_edgecolor('gray')
    
# Set the position and font of the legend
ax.legend(labels, bbox_to_anchor=(1.3,1.0), loc='center left', prop=font1)
​
# Set the figure to a circle
ax.set(aspect="equal")

Finally, you can get:

image

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