我有一个数据帧:
>>>df=pd.DataFrame(np.random.randn(3,3))
>>>df
0 1 2
0 -0.685692 0.180900 0.652838
1 0.484584 -0.441004 -1.617281
2 -0.665110 1.196987 -0.133439
例如,我想用长度为df.shape[0]
的序列s
的相应元素替换一行中的所有元素:
它适用于:
>>>df.where(df<=0, s, axis=0)
0 1 2
0 -0.685692 3.000000 3.000000
1 4.000000 -0.441004 -1.617281
2 -0.665110 5.000000 -0.133439
但是我的实际标准相当复杂,所以我想用一种积极的方式来陈述标准(而不是像上面的where
语句那样用<=0
而不是{
>>>df[df>0] = s
但是我得到的不是结果而是一个错误,axis
丢失了。如何在上面的语句中指定轴?在
错误消息:
Traceback (most recent call last):
Python Shell, prompt 97, line 1
File "/Users/a/anaconda/lib/python2.7/site-packages/pandas/core/frame.py", line 2297, in __setitem__
self._setitem_frame(key, value)
File "/Users/a/anaconda/lib/python2.7/site-packages/pandas/core/frame.py", line 2335, in _setitem_frame
self.where(-key, value, inplace=True)
File "/Users/a/anaconda/lib/python2.7/site-packages/pandas/core/generic.py", line 3940, in where
fill_value=np.nan)
File "/Users/a/anaconda/lib/python2.7/site-packages/pandas/core/frame.py", line 2680, in align
fill_axis=fill_axis, broadcast_axis=broadcast_axis)
File "/Users/a/anaconda/lib/python2.7/site-packages/pandas/core/generic.py", line 3784, in align
fill_axis=fill_axis)
File "/Users/a/anaconda/lib/python2.7/site-packages/pandas/core/generic.py", line 3870, in _align_series
raise ValueError('Must specify axis=0 or 1')
ValueError: Must specify axis=0 or 1
解决方案显而易见:
你只需要否定这个条件。有时坐在屏幕前太久会导致失明!
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