Numpy(Pandas)删除全为零的列的方法

时间:2021-05-22

在处理numpy数组,有这个需求,故写下此文:

使用np.argwhere和np.all来查找索引。要使用np.delete删除它们。

示例1

import numpy as npa = np.array([[1, 2, 0, 3, 0], [4, 5, 0, 6, 0], [7, 8, 0, 9, 0]])idx = np.argwhere(np.all(a[..., :] == 0, axis=0))a2 = np.delete(a, idx, axis=1)print(a2)"""[[1 2 3] [4 5 6] [7 8 9]]"""

示例2

import numpy as nparray1 = np.array([[1,0,1,0,0,0,0,0,0,1,1,0,0,0,1,1,0,1,0,0], [0,1,1,0,0,1,1,1,1,0,0,0,1,0,1,0,0,1,1,1], [0,0,1,0,0,1,1,1,0,0,0,0,0,0,0,1,0,0,1,1], [0,1,1,0,0,1,1,1,1,0,1,1,1,0,0,1,0,0,1,1], [0,0,1,0,0,1,1,1,0,1,0,1,1,0,1,1,0,0,1,0], [1,0,1,0,0,0,1,0,0,1,1,1,1,0,1,1,0,0,1,0], [1,0,1,0,1,1,0,0,0,0,1,0,0,0,1,0,0,0,1,1], [0,1,0,0,1,0,0,0,1,0,1,1,1,0,1,0,0,1,1,0], [0,1,0,0,1,0,0,1,1,0,1,1,1,0,0,1,0,1,0,0], [1,0,0,0,0,1,0,1,0,0,0,1,1,0,0,1,0,1,0,0]])mask = (array1 == 0).all(0)column_indices = np.where(mask)[0]array1 = array1[:,~mask]print("raw array", array1.shape) # raw array (10, 20)print("after array",array1.shape) # after array (10, 17)print("=====x=====\n",array1)

其它查看:https://moonbooks.org/Articles/How-to-remove-array-rows-that-contain-only-0-in-python/

pandas 删除全零列

from pandas import DataFramedf1=DataFrame(np.arange(16).reshape((4,4)),index=['a','b','c','d'],columns=['one','two','three','four']) # 创建一个dataframedf1.loc['e'] = 0 # 优雅地增加一行全0df1.ix[(df1==0).all(axis=1), :] # 找到它df1.ix[~(df1==0).all(axis=1), :] # 删了它

到此这篇关于Numpy(Pandas)删除全为零的列的方法的文章就介绍到这了,更多相关Numpy删除全为零的列内容请搜索以前的文章或继续浏览下面的相关文章希望大家以后多多支持!

声明:本页内容来源网络,仅供用户参考;我单位不保证亦不表示资料全面及准确无误,也不保证亦不表示这些资料为最新信息,如因任何原因,本网内容或者用户因倚赖本网内容造成任何损失或损害,我单位将不会负任何法律责任。如涉及版权问题,请提交至online#300.cn邮箱联系删除。

相关文章