Numpy的简单用法，下面就一起来了解一下
import numpy as np
一、创建ndarray对象
列表转换成ndarray:
>>> a = [1,2,3,4,5]
>>> np.array(a)
array([1, 2, 3, 4, 5])
取随机浮点数
>>> np.random.rand(3, 4)
array([[ 0.16215336, 0.49847764, 0.36217369, 0.6678112 ],
[ 0.66729648, 0.86538771, 0.32621889, 0.07709784],
[ 0.05460976, 0.3446
