Python Pandas-如何通过一个值过滤多列 [英] Python Pandas - How to filter multiple columns by one value

问题描述

我正在做熊猫分析.
我的表有7M行* 30列.单元格值的范围从-1到3随机.现在，我想根据列的值过滤出行.

我了解如何根据多个条件进行选择，写下条件并按&"组合"|".
但是我有30列要过滤，并且要按相同的值过滤.例如，需要选择最后12列的值等于-1

I am doing analysis by pandas.
My table has 7M rows* 30 columns. Cell values are ranged from -1 to 3 randomly. Now I want to filter out rows based on columns' value.

I understand how to select based on multiple conditions, write down conditions and combine by "&" "|".
But I have 30 columns to filter and filter by the same value. For instance, last 12 columns' value equals -1 need to be selected

df.iloc[:,-12:]==-1

上面的代码给了我一个布尔值.我需要实际的数据框.
此处的逻辑为或"，表示如果任何列的值为-1，则需要选择该行. 另外，很高兴知道我是否需要和"，所有列的值都为-1?
非常感谢

The code above gives me a boolean. I need actual data frame.
The logic here is "or", means if any column has value -1, that row needs to be selected. Also, it is good to know what if I need "and", all columns have value -1?
Many thanks

推荐答案

对于OR案例，请使用

For the OR case, use DF.any (returns True if any element is True along a particular axis):

df[(df.iloc[:,-12:] == -1).any(axis=1)]

对于AND情况，请使用 (如果所有元素沿特定轴为True，则返回True):

For the AND case, use DF.all (returns True if all elements are True along a particular axis):

df[(df.iloc[:,-12:] == -1).all(axis=1)]

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