基于多个条件删除行 Python Pandas
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Deleting rows based on multiple conditions Python Pandas
提问by fyr91
I want to delete rows when a few conditions are met:
我想在满足几个条件时删除行：
For instance, a random DataFrame is generated:
例如，生成一个随机数据帧：
import pandas as pd
import numpy as np
df = pd.DataFrame(np.random.randn(10, 4), columns=['one', 'two', 'three', 'four'])
print df
one instance of table is shown as below:
表的一个实例如下所示：
one two three four
0 -0.225730 -1.376075 0.187749 0.763307
1 0.031392 0.752496 -1.504769 -1.247581
2 -0.442992 -0.323782 -0.710859 -0.502574
3 -0.948055 -0.224910 -1.337001 3.328741
4 1.879985 -0.968238 1.229118 -1.044477
5 0.440025 -0.809856 -0.336522 0.787792
6 1.499040 0.195022 0.387194 0.952725
7 -0.923592 -1.394025 -0.623201 -0.738013
8 -1.775043 -1.279997 0.194206 -1.176260
9 -0.602815 1.183396 -2.712422 -0.377118
I want to delete rows based on the conditions that:
我想根据以下条件删除行：
Row with value of col 'one', 'two', or'three' greater than 0; andvalue of col 'four' less than 0 should be deleted.
列 'one'、'two'或'three' 的值大于 0 的行；并且应该删除小于 0 的 col 'four' 值。
Then I tried to implement as follows:
然后我尝试实现如下：
df = df[df.one > 0 or df.two > 0 or df.three > 0 and df.four < 1]
However, resulting in a error message as follow:
但是，导致错误消息如下：
ValueError: The truth value of an array with more than one element is ambiguous. Use a.any() or a.all()
Could someone help me on how to delete based on multiple conditions?
有人可以帮助我如何根据多个条件删除吗？
回答by Brionius
For reasons that aren't 100% clear to me, pandasplays nice with the bitwise logical operators |and &, but not the boolean ones orand and.
对于不是100％我清楚的原因，pandas起到很好的与位逻辑运算符|和&，而不是布尔类型的or和and。
Try this instead:
试试这个：
df = df[(df.one > 0) | (df.two > 0) | (df.three > 0) & (df.four < 1)]
