python - 如何防止数据在 matplotlib 散点图中拥挤在一起？

Question

我运行我的代码，然后得到下图。

当我修改图形选项的值时，我得到了我想要的输出。

我应该如何处理我的代码？如何在代码中设置左值和右值？

from matplotlib import pyplot as plt
import matplotlib.dates as mdate
import pandas as pd 
import numpy as np
import datetime
from decimal import Decimal
from pandas.plotting import register_matplotlib_converters
register_matplotlib_converters()

data =[(datetime.date(2019, 12, 23), Decimal('0.3230'), Decimal('157.89')),
       (datetime.date(2019, 12, 23), Decimal('0.1680'), Decimal('157.74')),  
       (datetime.date(2019, 12, 23), Decimal('0.1440'), Decimal('152.78')),  
       (datetime.date(2019, 12, 24), Decimal('0.1070'), Decimal('157.94')),  
       (datetime.date(2019, 12, 24), Decimal('0.6420'), Decimal('159.81')),   
       (datetime.date(2019, 12, 25), Decimal('0.0980'), Decimal('115.31')),   
       (datetime.date(2019, 12, 26), Decimal('0.0830'), Decimal('122.89')),    
       (datetime.date(2019, 12, 26), Decimal('0.1600'), Decimal('171.88')),   
       (datetime.date(2019, 12, 27), Decimal('0.1710'), Decimal('161.40')),   
       (datetime.date(2019, 12, 30), Decimal('0.0590'), Decimal('161.02')),   
       (datetime.date(2019, 12, 30), Decimal('0.4150'), Decimal('168.19')),   
       (datetime.date(2019, 12, 31), Decimal('0.1150'), Decimal('167.83')),   
       (datetime.date(2020, 1, 2), Decimal('0.0790'), Decimal('192.41')),   
       (datetime.date(2020, 1, 3), Decimal('0.4930'), Decimal('216.43')),   
       (datetime.date(2020, 1, 3), Decimal('0.2640'), Decimal('154.92')),   
       (datetime.date(2020, 1, 3), Decimal('0.1980'), Decimal('211.11')),   
       (datetime.date(2020, 1, 10), Decimal('0.2173'), Decimal('248.64')),   
       (datetime.date(2020, 1, 13), Decimal('1.3202'), Decimal('196.34')),   
       (datetime.date(2020, 1, 14), Decimal('0.0423'), Decimal('198.30')),   
       (datetime.date(2020, 1, 16), Decimal('0.0236'), Decimal('296.56')),   
       (datetime.date(2020, 1, 16), Decimal('0.0937'), Decimal('304.03'))]

df = pd.DataFrame(data)
df.rename(columns={0:'a',1:'b',2:'c'},inplace=True)
x = df.a
y = df.c
fig,ax=plt.subplots()
ax.scatter(x,y,facecolor='g',alpha=0.5)
ax.xaxis.set_major_formatter(mdate.DateFormatter('%Y-%m-%d'))
ax.set_xticks(x.drop_duplicates())
fig.autofmt_xdate()
plt.show()

Answer 1

您需要直接使用ax.set_xlim设置x轴限制。您可以从 x.drop_duplicates() 返回的数据帧中获取最大值和最小值，然后像这样填充一个小的时间增量

# ...
_x = x.drop_duplicates()
ax.set_xticks(_x)
# Create a 2-day timedelta and set the limits from the min and max with td as padding
td = datetime.timedelta(days=2)
ax.set_xlim([min(_x)-td, max(_x)+td])
fig.autofmt_xdate()
plt.show()

这会给你

我建议还设置一个更宽的数字，即

fig, ax = plt.subplots(figsize=(10, 5))

这会给你