python pandas 时间线图

Question

我有以下数据框

data_df = 
date          value
2016-01-15    1555
2016-01-16    1678
2016-01-17    1789
...  

我想创建一个时间线图，以日期为x轴

我导入可视化模块

import matplotlib.pyplot as plt
%matplotlib inline
import vincent as vin
import seaborn as sb

我尝试添加一列来格式化日期 data_df['日期'] = plt.date2num(ad_data.date)

然后我要绘制时间线 plot_date(data_df.dates, data_df.shown)

这不起作用，因为我没有正确转换日期。

Answer 1

您可以使用:

import pandas as pd
import matplotlib.pyplot as plt
import matplotlib.ticker as ticker

#sample data    
start = pd.to_datetime('2016-01-15')
rng = pd.date_range(start, periods=100)

data_df = pd.DataFrame({'date': rng, 'value': range(100)})  
data_df.value = data_df.value * 15 / data_df.date.dt.day
print (data_df)
         date        value
0  2016-01-15     0.000000
1  2016-01-16     0.937500
2  2016-01-17     1.764706
3  2016-01-18     2.500000
4  2016-01-19     3.157895
5  2016-01-20     3.750000
6  2016-01-21     4.285714
7  2016-01-22     4.772727
8  2016-01-23     5.217391
9  2016-01-24     5.625000
10 2016-01-25     6.000000
...
...

如有必要，将列 date 转换为 to_datetime然后 set_index来自 date 列:

data_df.date = pd.to_datetime(data_df.date)
data_df.set_index('date', inplace=True)
print (data_df)
                  value
date                   
2016-01-15     0.000000
2016-01-16     0.937500
2016-01-17     1.764706
2016-01-18     2.500000
2016-01-19     3.157895
2016-01-20     3.750000
2016-01-21     4.285714
2016-01-22     4.772727
2016-01-23     5.217391
2016-01-24     5.625000
2016-01-25     6.000000
...
...

绘制系列 data_df['value'] by plot然后设置轴 x 的格式:

ax = data_df['value'].plot()

ticklabels = data_df.index.strftime('%Y-%m-%d')
ax.xaxis.set_major_formatter(ticker.FixedFormatter(ticklabels))
plt.show()