Pandas 根据多个条件过滤行
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Pandas filter rows based on multiple conditions
提问by ArtDijk
I use pandas 0.13.1 Python 2.7:
我使用Pandas 0.13.1 Python 2.7：
I have some values in the riskcolumn that are neither, Small, Mediumor High. I want to delete the rows with the value not being Small, Mediumand High. I tried the following:
我在risk列中有一些值既不是 , Small,Medium也不是High。我想删除值不是Small,Medium和 的行High。我尝试了以下方法：
df = df[(df.risk == "Small") | (df.risk == "Medium") | (df.risk == "High")]
But this returns an empty data frame. How can I filter them correctly?
但这会返回一个空的数据框。如何正确过滤它们？
回答by EdChum
I think you want:
我想你想要：
df = df[(df.risk.isin(["Small","Medium","High"]))]
Example:
例子：
In [5]:
import pandas as pd
df = pd.DataFrame({'risk':['Small','High','Medium','Negligible', 'Very High']})
df
Out[5]:
risk
0 Small
1 High
2 Medium
3 Negligible
4 Very High
[5 rows x 1 columns]
In [6]:
df[df.risk.isin(['Small','Medium','High'])]
Out[6]:
risk
0 Small
1 High
2 Medium
[3 rows x 1 columns]
回答by Rafael
Another nice and readable approach is the following:
另一种不错的可读方法如下：
small_risk = df["risk"] == "Small"
medium_risk = df["risk"] == "Medium"
high_risk = df["risk"] == "High"
Then you can use it like this:
然后你可以像这样使用它：
df[small_risk | medium_risk | high_risk]
or
或者
df[small_risk & medium_risk]
