python pandas 空数据框

Question

短脚本需要这 2 个文件：

问题是获取 Date 的索引。我的索引总是空的

import pandas as pd
import numpy as np
import datetime as dt
import matplotlib.pyplot as plt
import pandas_datareader.data as web
import datetime
 
paper = pd.read_csv('PreisMoatStanley2013.dat',
                    delimiter = ' ',
                    parse_dates=[0,1,100,101])
 
 
 
data = pd.DataFrame({'GoogleWE': paper['Google End Date'],
                    'debt': paper['debt'].astype(np.float64),
                    'DJIADate': paper['DJIA Date'],
                    'DJIAClose': paper['DJIA Closing Price']
                    .astype(np.float64)})
data.set_index('DJIADate')
print paper [:5]
 
import quandl
#api_key = open('quandl_key.txt','r').read()
 
djia = pd.read_csv("djia.csv", index_col=0)
 
print djia[:3]
 
djia_closes = djia['Close'].reset_index()
djia_closes.set_index('Date')
print djia_closes[:3]
#s152
data = pd.merge(data, djia_closes,
left_on='DJIADate', right_on='Date')
data.drop(['DJIADate'], inplace=True, axis=1)
data = data.set_index('Date') # Problem seems to be here
 
print data[:3]

Shell 留言：

Empty DataFrame

Columns: [DJIAClose, GoogleWE, debt, Close]

Index: []

它应该是什么样子：

Date       /DJIAClose /GoogleWE  /debt /Close
2004-01-12 10485.18   2004-01-10 0.21  10485.2
2004-01-20 10528.66   2004-01-17 0.21  10528.7
2004-01-26 10702.51   2004-01-24 0.21  10702.5

来自data的数据：

  DJIAClose DJIADate   GoogleWE   debt
0 10485.18  2004-01-12 2004-01-10 0.210000
1 10528.66  2004-01-20 2004-01-17 0.210000
2 10702.51  2004-01-26 2004-01-24 0.210000 
3 10499.18  2004-02-02 2004-01-31 0.213333
4 10579.03  2004-02-09 2004-02-07 0.200000
5 10714.88  2004-02-17 2004-02-14 0.203333
6 10609.62  2004-02-23 2004-02-21 0.200000
7 10678.14  2004-03-01 2004-02-28 0.200000
8 10529.48  2004-03-08 2004-03-06 0.196667

数据来自djia_closes

Date       Close 
2004-01-02 10409.9
2004-01-08 10592.4
2004-01-09 10458.9
2004-01-12 10485.2
2004-01-13 10427.2
2004-01-14 10538.4
2004-01-20 10528.7
2004-01-26 10702.5

data.head()

  DJIAClose   DJIADate   GoogleWE  debt
0 10485.18 2004-01-12 2004-01-10 0.210000
1 10528.66 2004-01-20 2004-01-17 0.210000
2 10702.51 2004-01-26 2004-01-24 0.210000
3 10499.18 2004-02-02 2004-01-31 0.213333
4 10579.03 2004-02-09 2004-02-07 0.200000

djia_closes.head()

  Date    Close
0 2004-01-02 10409.9
1 2004-01-05 10544.1
2 2004-01-06 10538.7
3 2004-01-07 10529.0
4 2004-01-08 10592.4

Answer 1

您在读取 paper csv 时使用 parse_dates 选项，但在读取 djia csv 时不使用。这可能会导致您的问题 - "date" 列 data 是一个日期时间对象，但在 djia_close 中，日期只是一个字符串。所以没有任何匹配项，这就是为什么在合并它们时得到空数据框的原因。

尝试从 read_csv 中删除 parse_dates 看看会发生什么，或者尝试在合并之前将两个日期列都转换为日期时间对象。

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