今日作業：
   1、求文件a.txt中總共包含的字符個數？
   2、思考題  思考為何在第一次之後的n次sum求和得到的結果為0？
      with open(‘a.txt‘,encoding=‘utf-8‘) as f:
         g=(len(line) for line in f)
      print(sum(g))

   3、文件shopping.txt內容如下
      mac,2000,3
      lenovo,3000,10
      tesla,1000000,10
      chicken,200,1

      求總共花了多少錢？
      打印出所有的商品信息，格式為
      [{‘name‘:‘xxx‘,‘price‘:‘3333‘,‘count‘:3},....]
      求單價大於10000的商品信息，格式同上

   4、文件內容如下,標題為:姓名,性別,年紀,薪資
      egon male 18 3000
      alex male 38 30000
      wupeiqi female 28 20000
      yuanhao female 28 10000

      要求:
      從文件中取出每一條記錄放入列表中,
      列表的每個元素都是{‘name‘:‘egon‘,‘sex‘:‘male‘,‘age‘:18,‘salary‘:3000}的形式

   5 根據1得到的列表,取出薪資最高的人的信息
   6 根據1得到的列表,取出最年輕的人的信息
   7 根據1得到的列表,將每個人的信息中的名字映射成首字母大寫的形式
   8 根據1得到的列表,過濾掉名字以a開頭的人的信息

##1
sum_file = 0
with open(‘a.txt‘,encoding=‘utf-8‘) as f:
   for line in f:
       sum_file += len(line)
print(sum_file)

with open(‘a.txt‘,encoding=‘utf-8‘) as f:
    g=(len(line) for line in f)
    print(sum(g))

##2
#g是生成器，生成器的取值特性就是從頭到尾取完就結束，sum叠代取值第一次就取完了，所以後面g都是0，即sum也都是0

##3
total =0
with open(
 
‘shopping.txt‘,encoding=‘utf-8‘) as f:
    for line in f:
        line = line.strip(‘\n‘).split(‘,‘)
        price = int(line[1])*int(line[2])
        total += price
print(total)

with open(‘shopping.txt‘,encoding=‘utf-8‘) as f:
    g = (int(line.strip(‘\n‘).split(‘,‘)[1])*int(line.strip(‘\n‘).split(‘
 
,‘)[2]) for line in f)
    print(sum(g))

shopping_info = []
with open(‘shopping.txt‘,encoding=‘utf-8‘) as f:
    for line in f:
        line = line.strip(‘\n‘).split(‘,‘)
        keys = [‘name‘,‘price‘,‘count‘]
        d = {k:v for k,v in zip(keys,line)}
        shopping_info.append(d)
        print(d)
print(shopping_info)

shopping_info = []
with open(‘shopping.txt‘,encoding=‘utf-8‘) as f:
    for line in f:
        line = line.strip(‘\n‘).split(‘,‘)
        if int(line[1]) > 10000:
            keys = [‘name‘,‘price‘,‘count‘]
            d = {k:v for k,v in zip(keys,line)}
            shopping_info.append(d)
print(shopping_info)

##4
user_info = []
with open(‘4.txt‘,encoding=‘utf-8‘) as f:
    for line in f:
        line = line.split()
        keys = [‘name‘,‘sex‘,‘age‘,‘salary‘]
        d = {k:v for k,v in zip(keys,line)}
        user_info.append(d)
print(user_info)

##5
user_info = []
with open(‘4.txt‘,encoding=‘utf-8‘) as f:
    for line in f:
        line = line.split()
        keys = [‘name‘,‘sex‘,‘age‘,‘salary‘]
        d = {k:v for k,v in zip(keys,line)}
        user_info.append(d)
print(user_info)

salary_list = [int(index[‘salary‘]) for index in user_info]
# for index in user_info:
#     salary_list.append(int(index[‘salary‘]))
res = max(salary_list)
with open(‘4.txt‘,encoding=‘utf-8‘) as f:
    for line in f:
        if res == int(line.split()[3]):
            print(line)


##6
user_info = []
with open(‘4.txt‘,encoding=‘utf-8‘) as f:
    for line in f:
        line = line.split()
        keys = [‘name‘,‘sex‘,‘age‘,‘salary‘]
        d = {k:v for k,v in zip(keys,line)}
        user_info.append(d)
print(user_info)

age_info = (int(age[‘age‘]) for age in user_info)
# for age in user_info:
#     age = int(age[‘age‘])
#     age_info.append(age)

for info in user_info:
    if int(info[‘age‘]) == min(age_info):
        print(info)


##7
user_info = []
with open(‘4.txt‘, encoding=‘utf-8‘) as f:
    for line in f:
        line = line.split()
        keys = [‘name‘, ‘sex‘, ‘age‘, ‘salary‘]
        d = {k: v for k, v in zip(keys, line)}
        user_info.append(d)
print(user_info)

for name in user_info:
    name[‘name‘] = name[‘name‘].capitalize()
print(user_info)

##8
user_info = []
with open(‘4.txt‘, encoding=‘utf-8‘) as f:
    for line in f:
        line = line.split()
        keys = [‘name‘, ‘sex‘, ‘age‘, ‘salary‘]
        d = {k: v for k, v in zip(keys, line)}
        user_info.append(d)
print(user_info)

new_user_info = [aname for aname in user_info if not aname[‘name‘].startswith(‘a‘)]
# new_user_info = []
# for aname in user_info:
#     if not aname[‘name‘].startswith(‘a‘):
#         new_user_info.append(aname)
print(new_user_info)

python-code-14