訪問巢狀列表中的值
從三維列表開始:
alist = [[[1,2],[3,4]], [[5,6,7],[8,9,10], [12, 13, 14]]]
訪問列表中的專案:
print(alist[0][0][1])
#2
#Accesses second element in the first list in the first list
print(alist[1][1][2])
#10
#Accesses the third element in the second list in the second list
執行支援操作:
alist[0][0].append(11)
print(alist[0][0][2])
#11
#Appends 11 to the end of the first list in the first list
使用巢狀 for 迴圈列印列表:
for row in alist: #One way to loop through nested lists
for col in row:
print(col)
#[1, 2, 11]
#[3, 4]
#[5, 6, 7]
#[8, 9, 10]
#[12, 13, 14]
請注意,此操作可用於列表推導,甚至可用作生成器以提高效率,例如:
[col for row in alist for col in row]
#[[1, 2, 11], [3, 4], [5, 6, 7], [8, 9, 10], [12, 13, 14]]
並非外部列表中的所有專案都必須是列表本身:
alist[1].insert(2, 15)
#Inserts 15 into the third position in the second list
另一種使用巢狀 for 迴圈的方法。另一種方式更好但我偶爾需要使用它:
for row in range(len(alist)): #A less Pythonic way to loop through lists
for col in range(len(alist[row])):
print(alist[row][col])
#[1, 2, 11]
#[3, 4]
#[5, 6, 7]
#[8, 9, 10]
#15
#[12, 13, 14]
在巢狀列表中使用切片:
print(alist[1][1:])
#[[8, 9, 10], 15, [12, 13, 14]]
#Slices still work
最終名單:
print(alist)
#[[[1, 2, 11], [3, 4]], [[5, 6, 7], [8, 9, 10], 15, [12, 13, 14]]]