1.假设有20个学生，名字为westosx，学生分数在60-100之间，筛选出成绩在90分以上的学生

import random
stuInfo = {}
for i in range(20):
    name = 'westos' + str(i)
    score = random.randint(60,100)
    stuInfo[name] = score
print(stuInfo)
highscore = {}
for name,score in stuInfo.items():
    if score > 90:
        highscore[name] = score
print(highscore)

使用字典生成式

import random
stuInfo = {}
for i in range(20):
    name = 'westos' + str(i)
    score = random.randint(60,100)
    stuInfo[name] = score
print(stuInfo)
print({name: score for name,score in stuInfo.items() if score > 90})

2. 将所有的key值变为小写

例如：d = dict(a=1,b=2,c=2,B=9,A=10)，将所有key变为小写，并合并相同key的键值（a=11,b=11,c=2)

d = dict(a=1,b=2,c=2,B=9,A=10)
print(d)
new_d = {}
for i in d:
    new_d[i.upper()] = d[i]
print(new_d)
new_d = {}
for k,v in d.items():
    low_k = k.lower()
    if low_k not in new_d:
        new_d[low_k] = v
    else:
        new_d[low_k] += v
print(new_d)

字典生成式

d = dict(a=1,b=2,c=2,B=9,A=10)
print({k.lower(): (d.get(k.lower(),0) + d.get(k.upper(),0)) for k in d})