Matplotlib-平滑线

Question

我正在寻找有关如何平滑趋势线的建议。

这是代码：

import pandas as pd
from numpy import random

#Generating the data frame
df = pd.DataFrame(data = random.randn(5,4), index = ['A','B','C','D','E'],
columns = ['W','X','Y','Z'])

df['W'] = ['10/01/2018 12:00:00','10/03/2018 13:00:00',
           '10/03/2018 12:30:00','10/04/2018 12:05:00',
           '10/08/2018 12:00:15']

pd.to_datetime(df['W'])

print(df.head()) 

#Plotting hte graph
fig, ax = plt.subplots()
df.plot(x="W", y="X", ax=ax, color='salmon', alpha=0.5, marker='o')
df.plot(x="W", y="Y", ax=ax, color='royalblue', alpha=0.4, marker='o')

这就是我得到的：

我想得到一条平滑的线，像这样：

Answer 1

您可以使用df.resample方法和df.interpolate来完成您想要的事情。

首先，df.resample计算我们将进行插值的日期时间。之后，我们可以进行插值。

import pandas as pd
from numpy import random
import matplotlib.pyplot as plt

#Generating the data frame
df = pd.DataFrame(data = random.randn(5,4), index = ['A','B','C','D','E'], 
                                          columns = ['W','X','Y','Z'])

df['W'] = pd.to_datetime(['10/01/2018 12:00:00','10/03/2018 13:00:00',
                           '10/03/2018 12:30:00','10/04/2018 12:05:00',
                           '10/08/2018 12:00:15'], infer_datetime_format=True)

#Plotting
fig, ax = plt.subplots(1, 1)
df.plot(x="W", y="X", ax=ax, color='salmon', alpha=0.5, marker='o')
df.plot(x="W", y="Y", ax=ax, color='royalblue', alpha=0.4, marker='o')

df = df.resample('T', on='W').mean()

df.interpolate(method='spline', order=3, inplace=True)

df.plot(y='X', alpha=0.5, ax=ax, legend=False)
df.plot(y='Y',  alpha=0.4, ax=ax, legend=False)