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採取以下非常簡單的例子:熊貓合併上DatetimeIndex類型錯誤:類型的對象「NoneType」沒有LEN()
import pandas as pd
import numpy as np
import datetime
base = datetime.datetime(2016, 10, 1)
date_list = [base - datetime.timedelta(days=x) for x in range(0, 100)]
df1 = pd.DataFrame(np.random.randint(0,100,size=(100, 4)), columns=list('ABCD'), index = date_list)
df2 = pd.DataFrame(np.random.randint(0,100,size=(100, 4)), columns=list('ABCD'), index = date_list)
pd.merge(df1, df2, how = 'outer', left_on = True)
返回錯誤,類型錯誤:類型的對象「NoneType」沒有LEN( )。我是否缺少合併應該如何工作,如果我想合併索引上的這兩個DataFrame,這是相同的DatetimeIndex?
我運行的Python 2.7.12,熊貓0.18.1和1.11.1 numpy的
完整回溯是:
TypeError Traceback (most recent call last)
<ipython-input-1-3174c0ff542d> in <module>()
9 df2 = pd.DataFrame(np.random.randint(0,100,size=(100, 4)), columns=list('ABCD'), index = date_list)
10
---> 11 pd.merge(df1, df2, how = 'outer', left_on = True)
/Users/user/anaconda/lib/python2.7/site-packages/pandas/tools/merge.pyc in merge(left, right, how, on, left_on, right_on, left_index, right_index, sort, suffixes, copy, indicator)
36 right_on=right_on, left_index=left_index,
37 right_index=right_index, sort=sort, suffixes=suffixes,
---> 38 copy=copy, indicator=indicator)
39 return op.get_result()
40 if __debug__:
/Users/user/anaconda/lib/python2.7/site-packages/pandas/tools/merge.pyc in __init__(self, left, right, how, on, left_on, right_on, axis, left_index, right_index, sort, suffixes, copy, indicator)
208 (self.left_join_keys,
209 self.right_join_keys,
--> 210 self.join_names) = self._get_merge_keys()
211
212 def get_result(self):
/Users/user/anaconda/lib/python2.7/site-packages/pandas/tools/merge.pyc in _get_merge_keys(self)
405 left_keys, right_keys
406 """
--> 407 self._validate_specification()
408
409 left_keys = []
/Users/user/anaconda/lib/python2.7/site-packages/pandas/tools/merge.pyc in _validate_specification(self)
521 'of levels in the index of "left"')
522 self.left_on = [None] * n
--> 523 if len(self.right_on) != len(self.left_on):
524 raise ValueError("len(right_on) must equal len(left_on)")
525
TypeError: object of type 'NoneType' has no len()
此外,在這種情況下,最好是用'join'堅持,因爲它很好地連接上重疊的索引 - 'df1.join(df2,lsuffix ='_ l',rsuffix ='_ r')' –
謝謝!我必須完全錯誤地閱讀合併文檔。 –
'join'似乎也比合並速度稍微快一點'''''''''timeit df1.join(df2,lsuffix ='_ l',rsuffix ='_ r')'1000循環,最好是每循環3:468μs,'% timeit pd.merge(df1,df2,left_index = True,right_index = True)'返回1000個循環,每個循環最好爲3:485μs –