Matplotlib小册子：饼图概览

Table of Contents

1  官方Demo

2  将实际数据应用于官方Demo

3  一些改善措施

3.1  重新设置字体大小

3.2  设置显示颜色，Method 1：

3.3  设置显示颜色， Method 2：

3.4  设置图例（legend）

3.5  重新设置图例（legend）

3.6  将某些类别突出显示

前言

matplotlib， 官方提供的饼图Demo，功能比较比较简单，在实际应用过程中，往往会有许多个性化的绘制需求，在这里跟大家一起了解下饼图（pie chart）的一些特色的功能的实现。

1. from matplotlib import font_manager as fm

2. import matplotlib as mpl

3. import pandas as pd

4. import numpy as np

5. import matplotlib.pyplot as plt

6. % matplotlib inline

7. plt.style.use('ggplot')

1. 官方Demo

1. import matplotlib.pyplot as plt

2. # Pie chart, where the slices will be ordered and plotted counter-clockwise:

3. labels = 'Frogs', 'Hogs', 'Dogs', 'Logs'

4. sizes = [15, 30, 45, 10]

5. explode = (0, 0.1, 0, 0)  # only "explode" the 2nd slice (i.e. 'Hogs')

6. fig1, ax1 = plt.subplots()

7. ax1.pie(sizes, explode=explode, labels=labels, autopct='%1.1f%%',

8.        shadow=True, startangle=90)

9. ax1.axis('equal')  # Equal aspect ratio ensures that pie is drawn as a circle.

10. plt.savefig('Demo_official.jpg')

11. plt.show()

2. 将实际数据应用于官方Demo

1. # 原始数据

2. shapes = ['Cross', 'Cone', 'Egg', 'Teardrop', 'Chevron', 'Diamond', 'Cylinder',

3.       'Rectangle', 'Flash', 'Cigar', 'Changing', 'Formation', 'Oval', 'Disk',

4.       'Sphere', 'Fireball', 'Triangle', 'Circle', 'Light']

5. values = [  287,   383,   842,   866,  1187,  1405,  1495,  1620,  1717,

6.        2313,  2378,  3070,  4332,  5841,  6482,  7785,  9358,  9818, 20254]

7. s = pd.Series(values, index=shapes)

8. s

1. from matplotlib import font_manager as fm

2. import matplotlib as mpl

3. # Pie chart, where the slices will be ordered and plotted counter-clockwise:

4. labels = s.index

5. sizes = s.values

6. explode = (0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0)  # only "explode" the 1st slice

7. fig1, ax1 = plt.subplots()

8. patches, texts, autotexts = ax1.pie(sizes, explode=explode, labels=labels, autopct='%1.0f%%',

9.        shadow=False, startangle=170)

10. ax1.axis('equal')  # Equal aspect ratio ensures that pie is drawn as a circle.

11. plt.savefig('Demo_project.jpg')

12. plt.show()

上图的一些问题：

1. 颜色比较生硬

2. 部分文字拥挤在一起，绘图显示不齐整

3. 一些改善措施

• 重新设置字体大小

• 设置自选颜色

• 设置图例

• 将某些类别突出显示

3.1 重新设置字体大小

1. from matplotlib import font_manager as fm

2. import matplotlib as mpl

3. labels = s.index

4. sizes = s.values

5. explode = (0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0)  # only "explode" the 1st slice

6. fig1, ax1 = plt.subplots()

7. patches, texts, autotexts = ax1.pie(sizes, explode=explode, labels=labels, autopct='%1.0f%%',

8.        shadow=False, startangle=170)

9. ax1.axis('equal')  # Equal aspect ratio ensures that pie is drawn as a circle.

10. # 重新设置字体大小

11. proptease = fm.FontProperties()

12. proptease.set_size('xx-small')

13. # font size include: ‘xx-small’,x-small’,'small’,

14. # 'medium’,‘large’,‘x-large’,‘xx-large’ or number, e.g. '12'

15. plt.setp(autotexts, fontproperties=proptease)

16. plt.setp(texts, fontproperties=proptease)

17. plt.savefig('Demo_project_set_font.jpg')

18. plt.show()

3.2 设置显示颜色，Method 1：

1. from matplotlib import font_manager as fm

2. import matplotlib as mpl

3. # Pie chart, where the slices will be ordered and plotted counter-clockwise:

4. labels = s.index

5. sizes = s.values

6. explode = (0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0)  # only "explode" the 1st slice

7. fig1, ax1 = plt.subplots(figsize=(6,6)) # 设置绘图区域大小

8. a = np.random.rand(1,19)

9. color_vals = list(a[0])

10. my_norm = mpl.colors.Normalize(-1, 1) # 将颜色数据的范围设置为 [0, 1]

11. my_cmap = mpl.cm.get_cmap('rainbow', len(color_vals)) # 可选择合适的colormap，如：'rainbow'

12. patches, texts, autotexts = ax1.pie(sizes, explode=explode, labels=labels, autopct='%1.0f%%',

13.        shadow=False, startangle=170, colors=my_cmap(my_norm(color_vals)))

14. ax1.axis('equal')  

15. # 重新设置字体大小

16. proptease = fm.FontProperties()

17. proptease.set_size('xx-small')

18. # font size include: ‘xx-small’,x-small’,'small’,'medium’,‘large’,‘x-large’,‘xx-large’ or number, e.g. '12'

19. plt.setp(autotexts, fontproperties=proptease)

20. plt.setp(texts, fontproperties=proptease)

21. plt.savefig('Demo_project_set_color_1.jpg')

22. plt.show()

上面这种方法设置颜色时，但类别比较多时，部分颜色的填充会重复。

有时候，我们可能想设置成连续的颜色，可以有另外一种方法来实现。

3.3 设置显示颜色， Method 2：

1. from matplotlib import font_manager as fm

2. from  matplotlib import cm

3. labels = s.index

4. sizes = s.values

5. # explode = (0.2,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0)  # only "explode" the 1st slice

6. fig, ax = plt.subplots(figsize=(6,6)) # 设置绘图区域大小

7. colors = cm.rainbow(np.arange(len(sizes))/len(sizes)) # colormaps: Paired, autumn, rainbow, gray,spring,Darks

8. patches, texts, autotexts = ax.pie(sizes, labels=labels, autopct='%1.0f%%',

9.        shadow=False, startangle=170, colors=colors)

10. ax.axis('equal')  

11. ax.set_title('Shapes -------------------', loc='left')

12. # 重新设置字体大小

13. proptease = fm.FontProperties()

14. proptease.set_size('xx-small')

15. # font size include: ‘xx-small’,x-small’,'small’,'medium’,‘large’,‘x-large’,‘xx-large’ or number, e.g. '12'

16. plt.setp(autotexts, fontproperties=proptease)

17. plt.setp(texts, fontproperties=proptease)

18. plt.savefig('Demo_project_set_color_2.jpg')

19. plt.show()

从上图可以看出，颜色显示是连续的，实现了我们想要的效果

3.4 设置图例（legend）

1. from matplotlib import font_manager as fm

2. from  matplotlib import cm

3. labels = s.index

4. sizes = s.values

5. # explode = (0.2,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0)  # only "explode" the 1st slice

6. fig, ax = plt.subplots(figsize=(6,6)) # 设置绘图区域大小

7. colors = cm.rainbow(np.arange(len(sizes))/len(sizes)) # colormaps: Paired, autumn, rainbow, gray,spring,Darks

8. patches, texts, autotexts = ax.pie(sizes, labels=labels, autopct='%1.0f%%',

9.        shadow=False, startangle=170, colors=colors)

10. ax.axis('equal')  

11. # 重新设置字体大小

12. proptease = fm.FontProperties()

13. proptease.set_size('xx-small')

14. # font size include: ‘xx-small’,x-small’,'small’,'medium’,‘large’,‘x-large’,‘xx-large’ or number, e.g. '12'

15. plt.setp(autotexts, fontproperties=proptease)

16. plt.setp(texts, fontproperties=proptease)

17. ax.legend(labels, loc=2)

18. plt.savefig('Demo_project_set_legend_error.jpg')

19. plt.show()

从上面可看出，当类别较多时，图例（legend）的位置摆放显示有重叠，显示有些问题，需要进行调整。

3.5 重新设置图例（legend）

1. from matplotlib import font_manager as fm

2. from  matplotlib import cm

3. labels = s.index

4. sizes = s.values

5. # explode = (0.2,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0)  # only "explode" the 1st slice

6. fig, axes = plt.subplots(figsize=(10,5),ncols=2) # 设置绘图区域大小

7. ax1, ax2 = axes.ravel()

8. colors = cm.rainbow(np.arange(len(sizes))/len(sizes)) # colormaps: Paired, autumn, rainbow, gray,spring,Darks

9. patches, texts, autotexts = ax1.pie(sizes, labels=labels, autopct='%1.0f%%',

10.        shadow=False, startangle=170, colors=colors)

11. ax1.axis('equal')  

12. # 重新设置字体大小

13. proptease = fm.FontProperties()

14. proptease.set_size('xx-small')

15. # font size include: ‘xx-small’,x-small’,'small’,'medium’,‘large’,‘x-large’,‘xx-large’ or number, e.g. '12'

16. plt.setp(autotexts, fontproperties=proptease)

17. plt.setp(texts, fontproperties=proptease)

18. ax1.set_title('Shapes', loc='center')

19. # ax2 只显示图例（legend）

20. ax2.axis('off')

21. ax2.legend(patches, labels, loc='center left')

22. plt.tight_layout()

23. plt.savefig('Demo_project_set_legend_good.jpg')

24. plt.show()

3.6 将某些类别突出显示

• 将某些类别突出显示

• 控制label的显示位置

• 控制百分比的显示位置

• 控制突出位置的大小

1. from matplotlib import font_manager as fm

2. from  matplotlib import cm

3. labels = s.index

4. sizes = s.values

5. explode = (0.1,0,0,0,0,0,0,0,0,0,0,0,0,0.2,0,0,0,0.1,0)  # "explode" ， show the selected slice

6. fig, axes = plt.subplots(figsize=(8,5),ncols=2) # 设置绘图区域大小

7. ax1, ax2 = axes.ravel()

8. colors = cm.rainbow(np.arange(len(sizes))/len(sizes)) # colormaps: Paired, autumn, rainbow, gray,spring,Darks

9. patches, texts, autotexts = ax1.pie(sizes, labels=labels, autopct='%1.0f%%',explode=explode,

10.        shadow=False, startangle=170, colors=colors, labeldistance=1.2,pctdistance=1.03, radius=0.4)

11. # labeldistance: 控制labels显示的位置

12. # pctdistance: 控制百分比显示的位置

13. # radius: 控制切片突出的距离

14. ax1.axis('equal')  

15. # 重新设置字体大小

16. proptease = fm.FontProperties()

17. proptease.set_size('xx-small')

18. # font size include: ‘xx-small’,x-small’,'small’,'medium’,‘large’,‘x-large’,‘xx-large’ or number, e.g. '12'

19. plt.setp(autotexts, fontproperties=proptease)

20. plt.setp(texts, fontproperties=proptease)

21. ax1.set_title('Shapes', loc='center')

22. # ax2 只显示图例（legend）

23. ax2.axis('off')

24. ax2.legend(patches, labels, loc='center left')

25. plt.tight_layout()

26. # plt.savefig("pie_shape_ufo.png", bbox_inches='tight')

27. plt.savefig('Demo_project_final.jpg')

28. plt.show()

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