Python学习笔记：List、Tuple、for循环

1.list

list_demo = [7, 7, 8, 9, 9, 9]
print(list_demo.index(7))       # index 方法返回第一个index
list_demo.sort()                # 排序list
list_demo.reverse()             # 倒序list
list_demo1 = list_demo.copy()   # 复制list

 

2.matrix

其实就是list嵌套，可以使用双重for遍历，所包含方法与list一致

matrix = [[1, 2, 3], [4, 5, 6], [7, 8, 9]]
print(matrix[0][0])
for row in matrix:
    for i in row:
        print(i)

1
1
2
3
4
5
6
7
8
9

Process finished with exit code 0

3.for循环实例：随机生成一个固定大小的list，并找到list中最大的数和对应的index

import random
list_demo = []
for i in range(10):
    list_demo.append(random.randint(0, 100))
max_num = list_demo[0]
print(list_demo)
for i in list_demo:
    if i >= max_num:
        max_num = i
print(f"Max_Num = list_demo[{list_demo.index(max_num)}] = {max_num}")

4.for循环实例：删除list中重复的元素

list_num = [1, 1, 2, 3, 4, 5, 3, 1]
list_copy = []
for i in list_num:
    if i not in list_copy:
        list_copy.append(i)
print(list_copy)

 5.tuple

tuple不可变，但是可以多个tuple拼接组合

tuple_demo = (1, 2, 3, 1, 1)        # tuple不可变
tuple_demo.index(1)
tuple_demo.count(1)
coordinates = (1, 2, 3)
x, y, z = coordinates               # python优势，string\list\tuple等都可以
msg = 'string'
a, b, c = msg[0:3]
print()

6.dictionary

{key:value}

dic_demo = {"name": "abc", "age": 25, "is_verified": True, "birth_year": 1998}
print(dic_demo["name"])
print(dic_demo.get("age"))
print(dic_demo.get("1sad4"))
print(dic_demo.get("birth_year"))
print(dic_demo)

abc
25
None
1998
{'name': 'abc', 'age': 25, 'is_verified': True, 'birth_year': 1998}

Process finished with exit code 0

 7.dictionary application: Translate the input number into English

input默认是string，可以直接遍历string建立string：string的dictionary，也可以将input变为int，建立int：string的dictionary

define的method是将数字拆分单个数的组成的list

dic_demo = {
    1: "one",
    2: "two",
    3: "three",
    4: "four",
    5: "five",
    6: "six",
    7: "seven",
    8: "eight",
    9: "nine",
    0: "zero"
}
dic_demo1 = {
    "1": "one",
    "2": "two",
    "3": "three",
    "4": "four",
    "5": "five",
    "6": "six",
    "7": "seven",
    "8": "eight",
    "9": "nine",
    "0": "zero"
}
string_num = input("Please input the numbers:")


# string方法
string_ans = ""
for i in string_num:
    string_ans = string_ans+dic_demo1[i]+" "
print(string_ans)


def nums_to_single(nums_demo):
    nums_ans = []
    if nums_demo == 0:
        nums_ans.append(0)
    while nums_demo > 0:
        nums_ans.append(nums_demo % 10)
        nums_demo = int(nums_demo / 10)
    nums_ans.reverse()
    return nums_ans


# int方法
string_ans1 = ""
int_num = int(string_num)
num_list = nums_to_single(int_num)
for i in num_list:
    string_ans1 = string_ans1+dic_demo[i]+" "
print(string_ans1)