1、使用有名字的切片操作文本文件效率很高。

invoice = """
 0.....6.................................40........52...55........
1909   Pimoroni PiBrella                   $17.50    3    $52.50
1489   6mm Tactile Switch x20              $4.95     2    $9.90
1510   Panavise Jr. - PV-201               $28.00    1    $28.00
1601   PiTFT Mini Kit 320x240              $34.95    1    $34.95
"""
SKU = slice(0, 6)
DESCRIPTION = slice(6, 40)
UNIT_PRICE = slice(40, 52)
QUANTITY = slice(52, 55)
ITEM_TOTAL = slice(55, None)   #None 表示到最后
line_items = invoice.split('\n')[2:]
for item in line_items:
    print(item[UNIT_PRICE], item[DESCRIPTION])

2、...可以作為多維切片的快捷方法，代表該維度全取（：）。

import numpy as np
a=np.array([[[1,2,3],[4,5,6]],[[7,8,9],[10,11,12]]])
a[:,:,1:]
Out[50]: 
array([[[ 2,  3],
        [ 5,  6]],

       [[ 8,  9],
        [11, 12]]])
a[...,1:]
Out[52]: 
array([[[ 2,  3],
        [ 5,  6]],

       [[ 8,  9],
        [11, 12]]])