从元组列表中的python bar plot

Question

非常新手的问题:

我需要从元组列表中绘制条形图.第一个元素是x轴的名称(分类),第二个元素是float类型(对于y轴).我还想按降序排列条形图,并添加趋势线.以下是一些示例代码:

In [20]: popularity_data
Out[20]: 
[('Unknown', 10.0),
 (u'Drew E.', 240.0),
 (u'Anthony P.', 240.0),
 (u'Thomas H.', 220.0),
 (u'Ranae J.', 150.0),
 (u'Robert T.', 120.0),
 (u'Li Yan M.', 80.0),
 (u'Raph D.', 210.0)]

Answer 1

如果你有一个元组列表,你可以尝试下面的代码来获得你想要的.

import numpy as np
import matplotlib.pyplot as plt
popularity_data = [('Unknown', 10.0),
     (u'Drew E.', 240.0),
     (u'Anthony P.', 240.0),
     (u'Thomas H.', 220.0),
     (u'Ranae J.', 150.0),
     (u'Robert T.', 120.0),
     (u'Li Yan M.', 80.0),
     (u'Raph D.', 210.0)]

# sort in-place from highest to lowest
popularity_data.sort(key=lambda x: x[1], reverse=True) 

# save the names and their respective scores separately
# reverse the tuples to go from most frequent to least frequent 
people = zip(*popularity_data)[0]
score = zip(*popularity_data)[1]
x_pos = np.arange(len(people)) 

# calculate slope and intercept for the linear trend line
slope, intercept = np.polyfit(x_pos, score, 1)
trendline = intercept + (slope * x_pos)

plt.plot(x_pos, trendline, color='red', linestyle='--')    
plt.bar(x_pos, score,align='center')
plt.xticks(x_pos, people) 
plt.ylabel('Popularity Score')
plt.show()

这将为您提供类似下图的情节,但是当您不使用时间序列时,在条形图上绘制趋势线是没有意义的.

参考文献:

• Python:元组的情节列表
• matplotlib api示例代码:barchart_demo.py
• 用Matplotlib和Numpy练习