The Python list matrix defines and uses the

In Python, unlike C, the C language uses any variable to define its type (int a = 1), and Python can directly assign a value without defining (A = 1). However, to use a matrix, it is also defined when you assign a value directly. (Do not know if you can read, do not understand, you can not see, see below directly.) ）

1. Definition matrix

>>> Import NumPy
>>> Import NumPy as NP
>>> y=np.empty ([2,2],dtype=int) #表示定义一个2 the *2 matrix, which is an integral type

2. Definition List

Method One:

>>> l=[] #该定义的列表长度是未知的
>>> l.append (' a ') #用append函数加入数据
>>> L
[' A ']

Method Two:

>>> L=range (#该定义的列表长度是已知的)
>>> l[3]= ' a ' #可以用该种方法向列表中赋值
>>> L
[0, 1, 2, ' a ', 4, 5, 6, 7, 8, 9]