初始字典如下：

dic = {"k1": "v1", "k2": "v2", "k3": "v3"}

完成以下练习题目

#?遍历字典 dic 中所有的key
for ele in dic.keys():
    print(ele)

#?b.遍历字典 dic 中所有的value
for ele in dic.values():
    print(ele)

#?c.循环遍历字典 dic 中所有的key和value
for k,v in dic.items():
    print(k,v)

#?添加一个键值对"k4","v4",输出添加后的字典 dic
dic["k4"] = "v4"
print(dic)

#?e.删除字典 dic 中的键值对"k1","v1",并输出删除后的字典 dic
del dic["k1"]
print(dic)

#?f.删除字典 dic 中 'k5' 对应的值，若不存在，使其不报错，并返回None
if "K5" in ele:
    del dic["k5"]
else:
    print(dic.get("k5"))

#?g.获取字典 dic 中“k2”对应的值
print(dic["k2"])
print(dic.get("k2","0.0"))

新增一个字典如下：使得dic2 = {'k1':"v111",'k2':"v2",'k3':"v3",'k4': 'v4','a':"b"}

dic2 = {'k1':"v111",'a':"b"}
#两种方法
# ? 使用update()
dic2= {'k1':"v111",'a':"b"} 
dic2.update({'k1':"v111",'k2':"v2",'k3':"v3",'k4': 'v4','a':"b"})
print(dic2)

# ?使用items()
dic = {'k2': 'v2', 'k3': 'v3', 'k4': 'v4'}
dic2 = {'k1':"v111",'a':"b"}
del dic2["a"]
#ele_list = list(dic2.keys())
for k,v in dic.items():
    dic2[k] = v
dic2["a"] = "b"
print(dic2)

2.已知列表list1 = [11,22,11,33,44,55,66,55,66],
统计列表中每个元素出现的次数，生成一个字典，结果为{11:2,22:1.....}

list1 = [11,22,11,33,44,55,66,55,66]
new_dic = {}
for ele in list1:
    new_dic[ele] = list1.count(ele)
print(new_dic)

3.已知如下列表students，在列表中保存了6个学生的信息，根据要求完成下面的题目

students = [
{'name': '小花', 'age': 19, 'score': 90, 'gender': '女', 'tel':
'15300022839'},
{'name': '明明', 'age': 20, 'score': 40, 'gender': '男', 'tel':
'15300022838'},
{'name': '华仔', 'age': 18, 'score': 90, 'gender': '女', 'tel':
'15300022839'},
{'name': '静静', 'age': 16, 'score': 90, 'gender': '不明', 'tel':
'15300022428'},
{'name': 'Tom', 'age': 17, 'score': 59, 'gender': '不明', 'tel':
'15300022839'},
{'name': 'Bob', 'age': 18, 'score': 90, 'gender': '男', 'tel':
'15300022839'}
]

使用循环知识点，以及建立变量名的规范

#? 统计不及格学生的个数
fail_stu = 0
for ele in students:
    if ele["score"] <= 60:
        fail_stu +=1
print(fail_stu)    

#? b.打印不及格学生的名字和对应的成绩
stu_dic = {}
for ele in students:
    if ele["score"] <= 60:
        stu_dic[ele["name"]] = ele["score"]
print(stu_dic)

#? c.统计未成年学生的个数
minor_stu = 0
for ele in students:
    if ele["age"] < 18:
        minor_stu +=1
print(minor_stu)

#? d.打印手机尾号是8的学生的名字
for ele in students:
    if ele["tel"][-1] == "8":
        print(ele["name"])
    
#? e.打印最高分和对应的学生的名字
maxscore_stu =[]
stu_score = {}
max_score = 0
for ele in students:
    maxscore_stu.append(ele["score"])
    max_score = max(maxscore_stu)
for ele in students:
    if ele["score"] == max_score:
        stu_score[ele["name"]] = max_score
print(stu_score)

#? f.删除性别不明的所有学生
new_dic = []
for ele in students:
    if ele["gender"] != "不明":
        new_dic.append(ele)
print(new_dic)

#? g.将列表按学生成绩从大到小排序
students.sort(key = lambda x:x["score"])
print(students)

4.使用列表推导式完成下面的题目

#? a. 生成一个存放1-100之间个位数为3的数据列表
print( [ele for ele in range(3,94,10)])

#?b. 利用列表推导式将已知列表中的整数提取出来
#?[17, 98, 34, 21]
list_two = [True, 17, "hello", "bye", 98, 34, 21] 
print([ele for ele in list_two if type(ele) == int])

#?利用列表推导式存放指定列表中字符串的长度
#? --- [4, 4, 7, 3]
list_three=["good", "nice", "see you", "bye"] 
print([len(ele) for ele in list_three])

#? d.生成一个列表，其中的元素为'0-1'，'1-2'，'2-3'，'3-4'，'4-5'
print([str(i)+"-"+str(i+1) for i in range(0,5)])
print([f"{i}_{i+1}" for i in range(0,5)])

5. dict_list = [{“科目”:“政治”, “成绩”:98}, {“科目”:“语文”, “成绩”:77}, {“科目”:“数学”, “成绩”:99}, {“科目”:“历史”, “成绩”:65}]，
# 去除列表中成绩小于70的字典 【列表推导式完成】

dict_list = [
{"科目":"政治", "成绩":98}, 
{"科目":"语文", "成绩":77}, 
{"科目":"数学", "成绩":99}, 
{"科目":"历史", "成绩":65}]

dict_list.remove([ele for ele in dict_list[::] if ele["成绩"]<70][0])
print(dict_list)

6.用三个列表表示三门学科的选课学生姓名(一个学生可以同时选多门课)

subject_list = {
    # a,b,c...分别代表学生姓名，1，2，3代表课程
    'a': ['1', '2', '3'],
    'b': ['1', '3'],
    'c': ['1', '2'],
    'd': ['3'],
    'e': ['2', '3'],
    'f': ['2', '3']
}
#?a. 求选课学生总共有多少人
print(f"选课学生共有：{len(subject_list)}人")

#?b. 求只选了第一个学科的人的数量和对应的名字
#?c. 求只选了一门学科的学生的数量和对应的名字
#?d. 求只选了两门学科的学生的数量和对应的名字
#?e. 求选了三门学生的学生的数量和对应的名字

count_one = 0
count_only = 0
count_two = 0
count_only_three = 0
for k,v in subject_list.items():
    if "1" in v:
        count_one +=1
        print(f"选择第一个学科的名字是 :{k}")
print(f"选课第一个学科的人的数量: {count_one}")
print("-------------------------'")
for k,v in subject_list.items():
    if len(v) == 1:
        count_only +=1
        print(f"只选了一门学科的学生名字是 :{k}")
print(f"只选了一门学科的学生数量: {count_only}")
print("-------------------------'")
for k,v in subject_list.items():
    if len(v) == 2:
        count_two +=1
        print(f"只选了两门学科的学生名字是 :{k}")
print(f"只选了两门学科的学生的数量: {count_two}")
print("-------------------------'")
for k,v in subject_list.items():
    if len(v) == 3:
        count_only_three +=1
        print(f"三门学生的学生名字是 :{k}")
print(f"三门学生的学生的数量数量: {count_only_three}")
print("-------------------------'")

以上的练习题，从简到难，都是我学习过程中的一些练习题，提供给正在学习Python的小伙伴，想要做的话，一定要自己手敲一遍，我写的答案是正确的，但是每个人的思维是不一样的，欢迎一起探讨。