np_0312.py

# # -*- coding: utf-8 -*-
# """
# Created on Mon Mar 12 17:09:32 2018
#
# @author: hasee_yang
#
# 向量化的编程（矢量化的编程）
# """
#
# import numpy as np
# # =============================================================================
# #
# # b = np.arange(24).reshape(2,3,4)
# # b1 = np.arange(24).reshape(2,2,2)
# # print(b)
# # print(b1)
# # print(b[0,0,1])
# # =============================================================================
#
# # 数组与标量的运算
# arr = np.array([[1., 2., 3.], [4., 5.,6.]])
# arr
# arr1 = arr * arr
# arr2 = arr + arr
#
# arr3 = 1/arr
# print(arr)
# # =============================================================================
# #print(arr1)
# print(arr2)
# # print(arr3)
# # =============================================================================

lst = [[1, 2, 3, 4], [5, 6, 7, 8], [9, 10, 11, 12]]
print(len(lst[3]))