Python_二维数组

例1：将数组旋转90度

a = [[i for i in range(4,8)] for n in range(4,8)]
print(a)
# 遍历大序列
for a_index, w in enumerate(a):            # enumaerate()遍历数据对象，同时列出数据和数据下标
     # 遍历大序列里的小序列
    for w_index in range(a_index, len(w)):    # range(w_index, )使for循环从w_index行开始替换
        tmp = a[w_index][a_index]      # 将大序列里的值存起来
        a[w_index][a_index] = w[w_index]          # 将小序列的值放到大序列
        a[a_index][w_index] = tmp            #将存起来的值放到小序列里
    print('----------------')
    for r in a:                         #查看转换过程
        print(r)

结果：

[[4, 5, 6, 7], [4, 5, 6, 7], [4, 5, 6, 7], [4, 5, 6, 7]]
----------------
[4, 4, 4, 4]
[5, 5, 6, 7]
[6, 5, 6, 7]
[7, 5, 6, 7]
----------------
[4, 4, 4, 4]
[5, 5, 5, 5]
[6, 6, 6, 7]
[7, 7, 6, 7]
----------------
[4, 4, 4, 4]
[5, 5, 5, 5]
[6, 6, 6, 6]
[7, 7, 7, 7]
----------------
[4, 4, 4, 4]
[5, 5, 5, 5]
[6, 6, 6, 6]
[7, 7, 7, 7]