一、概念
二维列表的元素还是列表（列表的嵌套），称之为二维列表。

需要通过行标和列标来访问二维列表的元素

二、创建二维列表

1、追加一维列标来生成二维列标
生成一个4行3列的二维列表

row1 = [3, 4, 5]
row2 = [1, 5, 9]
row3 = [2, 5, 8]
row4 = [7, 8, 9]
matrix = []
matrix.append(row1)
matrix.append(row2)
matrix.append(row3)
matrix.append(row4)
print(matrix)

输出结果：

[[3, 4, 5], [1, 5, 9], [2, 5, 8], [7, 8, 9]]

2、直接赋值生成二维列表
定义一个3行4列的二维列表

matrix = [[], [], []]
matrix[0] = [3, 4, 5, 6]
matrix[1] = [8, 7, 9, 5]
matrix[2] = [0, 2, 5, 8]
print(matrix)

输出结果：

[[3, 4, 5, 6], [8, 7, 9, 5], [0, 2, 5, 8]]

三、一维列标与二维列表的转换

1、一维列表转换成二维列表
将1到24的全部数字按顺序放到一个4行6列的二维列表里

# 将1到24的全部数字按顺序放到一个4行6列的二维列表里
nums = []
for i in range(1, 25):
    nums.append(i)
 
martix = []
for k in range(4):
    row = []
    for j in range(1, 7):
        row.append(j + 6 * k)
    martix.append(row)
 
for arr in martix:
    print(arr)

输出结果：

[1, 2, 3, 4, 5, 6]
[7, 8, 9, 10, 11, 12]
[13, 14, 15, 16, 17, 18]
[19, 20, 21, 22, 23, 24]

2、二维列表转换成一维列表
将一个3行5列的二维列表扁平化一维列表

# 将一个3行5列的二维列表扁平化一维列表
nums = [[1, 2, 3, 4, 5], [6, 7, 8, 9, 10], [11, 12, 13, 14, 15]]
arr = []
for i in nums:
    for j in i:
        arr.append(j)
print(arr)

输出结果：

[1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15]

3、利用NumPy实现数组的变维操作
利用NumPy数组提供的 reshape(m, n) 实现数组的变维

（1）一维数组变成二维数组

In [31]:import numpy as np
 
In [32]:arr1 = np.arange(1,25)  # arange() 创建一个等差数组
 
In [33]:arr2 = arr1.reshape(4, 6)  # reshape（）一维转二维
 
In [34]:arr2
Out[34]: 
array([[ 1,  2,  3,  4,  5,  6],
       [ 7,  8,  9, 10, 11, 12],
       [13, 14, 15, 16, 17, 18],
       [19, 20, 21, 22, 23, 24]])
 
In [35]:arr2 = arr1.reshape(3, 8)
 
In [36]:arr2
Out[36]: 
array([[ 1,  2,  3,  4,  5,  6,  7,  8],
       [ 9, 10, 11, 12, 13, 14, 15, 16],
       [17, 18, 19, 20, 21, 22, 23, 24]]) 

（2）二维数组转换成一维数组

In [36]:arr2
Out[36]: 
array([[ 1,  2,  3,  4,  5,  6,  7,  8],
       [ 9, 10, 11, 12, 13, 14, 15, 16],
       [17, 18, 19, 20, 21, 22, 23, 24]])
 
In [37]:arr1 = arr2.reshape(1, 24)[0]
 
In [38]:arr1
Out[38]: 
array([ 1,  2,  3,  4,  5,  6,  7,  8,  9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24])

四、访问二维列表
通过行标与列标来访问二维列表（可以通过切片运算访问行）

1、访问行

In [36]:arr2
Out[36]: 
array([[ 1,  2,  3,  4,  5,  6,  7,  8],
       [ 9, 10, 11, 12, 13, 14, 15, 16],
       [17, 18, 19, 20, 21, 22, 23, 24]])
 
In [39]:arr2[1]
Out[39]: array([ 9, 10, 11, 12, 13, 14, 15, 16])

2、访问元素

In [40]:arr2
Out[40]: 
array([[ 1,  2,  3,  4,  5,  6,  7,  8],
       [ 9, 10, 11, 12, 13, 14, 15, 16],
       [17, 18, 19, 20, 21, 22, 23, 24]])
 
In [41]:arr2[1][2]  # 第2行第3列
Out[41]: 11

3、NumPy二维数组的访问

In [42]:import numpy as np
 
In [43]:arr2
Out[43]: 
array([[ 1,  2,  3,  4,  5,  6,  7,  8],
       [ 9, 10, 11, 12, 13, 14, 15, 16],
       [17, 18, 19, 20, 21, 22, 23, 24]])
 
In [44]:arr2[1]  # 访问行
Out[44]: array([ 9, 10, 11, 12, 13, 14, 15, 16])
 
In [45]:arr2[:, 0]  # 访问列
Out[45]: array([ 1,  9, 17])
 
In [46]:arr2[2, 3]  # 访问元素
Out[46]: 20

总结 以上为个人经验，希望能给大家一个参考，也希望大家多多支持。

原文链接：https://blog.csdn.net/realoser/article/details/122154362