Python——二維數組遍歷操作

 

一、遍歷數組（操作Value）

1.使用二維列表遍歷二維數組

python 創建List二維列表

lists = [[] for i in range(3)]  # 創建的是多行三列的二維列表
for i in range(3):
    lists[0].append(i)
for i in range(5):
    lists[1].append(i)
for i in range(7):
    lists[2].append(i)
print("lists is:", lists)
# lists is: [[0, 1, 2], [0, 1, 2, 3, 4], [0, 1, 2, 3, 4, 5, 6]]

 輸出數組行和列數

# 輸出數組的行和列數
arr = [[1,4,7,10,15], [2,5,8,12,19], [3,6,9,16,22], [10,13,14,17,24]]
print arr.shape  # (4, 5)
# 只輸出行數
print arr.shape[0] # 4
# 只輸出列數
print arr.shape[1] # 5

或者：

In [48]: arr = [[1,4,7,10,15], [2,5,8,12,19], [3,6,9,16,22], [10,13,14,17,24]]

In [49]: len(arr)  #行數
Out[49]: 4

In [50]: len(arr[0])　#列數
Out[50]: 5

 

---

使用二維列表索引遍歷二維列表

• 注意python中二維列表和matlab以及C和JAVA中一樣，不需要每行中列的數量相等

 

sum_0 = 0
for i in range(len(lists)):
    for j in range(len(lists[i])):
        print(lists[i][j])
        sum_0 += lists[i][j]
print("The sum_0 of Lists:", sum_0)

# 0
# 1
# 2
# 0
# 1
# 2
# 3
# 4
# 0
# 1
# 2
# 3
# 4
# 5
# 6
# The sum of Lists: 34

---

使用二維列表句柄遍歷二維列表

sum_1 = 0
for i in lists:
    for j in i:
        sum_1 += j

print("The sum_1 of Lists:", sum_1)
# The sum_1 of Lists: 34

 

2.利用二維列表索引（類似C++）

 注：一定要確保二維列表每行列數相同，否則會報錯。因爲Python允許二維數組列數不同

import numpy as np
world=np.zero([5,5])
for i in range(0,world.shape[0])
    for j in range(0,world.shape[1])
        print (world[i][j])

3.利用列表句柄

list2d = [[1,2,3],[4,5]]
sum = 0
for i in list2d:
    for j in i:
        sum += j