1. 通过 sql 语句筛选出符合条件的数据
condition_dict = {'name': 1, 'id': 0, 'age': 2, 'phone': 3, 'job': 4}
def get_data():
'''
获取文件中的数据
:return: 生成器
'''
with open('staff', encoding='utf-8') as f:
for i, l in enumerate(f):
if i > 0:
yield l.strip().split(',')
def condition_fn(c):
'''
根据条件进行筛选
:param c: 条件的字符串 -> age > 10
:return: 符合条件的列表
'''
if '>' in c:
col, val = c.split('>')
g = get_data()
for i in g:
if int(i[condition_dict[col]]) > int(val):
yield i
elif '<' in c:
col, val = c.split('<')
g = get_data()
for i in g:
if int(i[condition_dict[col]]) < int(val):
yield i
elif '=' in c:
col, val = c.split('=')
g = get_data()
for i in g:
if i[condition_dict[col]] == val:
yield i
def show_data(view_list, field):
'''
展示符合条件的员工数据
:param view_list: 符合条件的员工信息生成器
:param field: name,age
:return:
'''
if '*' in field:
for i in view_list:
print(i)
else:
f_name = field.split('select')
f_name_arr = f_name[1].strip().split(',')
for i in view_list:
for n in f_name_arr:
print(i[condition_dict[n]], end=' ')
print('')
ret = 'select name,age where age<23'
field, condition = ret.split('where')
view_list = condition_fn(condition.strip())
show_data(view_list, field.strip())
# staff
id,name,age,phone,job
1,Alex,22,13651054608,IT
2,Egon,23,13304320533,Tearcher
3,nezha,25,1333235322,IT
2. 三级菜单
menu = {
'北京': {
'海淀': {
'五道口': {
'soho': {},
'网易': {},
'google': {}
},
'中关村': {
'爱奇艺': {},
'汽车之家': {},
'youku': {},
},
'上地': {
'百度': {},
},
},
'昌平': {
'沙河': {
'老男孩': {},
'北航': {},
},
'天通苑': {},
'回龙观': {},
},
'朝阳': {},
'东城': {},
},
'上海': {
'闵行': {
"人民广场": {
'炸鸡店': {}
}
},
'闸北': {
'火车战': {
'携程': {}
}
},
'浦东': {},
},
'山东': {},
}
def threeLM(dic):
while True:
for k in dic: print(k)
content = input('>>> ').strip()
if content == 'q':
break
elif content in dic:
print(dic[content])
threeLM(dic[content])
else:
threeLM(menu)
threeLM(menu)
3. 计算器
import re
def dealwith(express):
# 对表达式中的符号进行处理 +- 替换成 - ，-- 替换成 +
express = express.replace('+-', '-')
express = express.replace('--', '+')
return express
def cal_exp_son(exp_son):
# 用来计算原子型的表达式 两个数之间的乘除法
if '/' in exp_son:
a, b = exp_son.split('/')
return str(float(a) / float(b))
else:
a, b = exp_son.split('*')
return str(float(a) * float(b))
def cal_express_no_breacket(exp):
# 计算没有括号的表达式
# exp是没有经过处理的最内层带括号的表达式
exp = exp.strip('()')
while True:
ret = re.search(r'\d+\.?\d*[*/]-?\d+\.?\d*', exp) # 匹配第一个乘除
if ret: # 判断表达式中是否还有乘除
exp_son = ret.group()
print(exp_son)
ret = cal_exp_son(exp_son)
exp = exp.replace(exp_son, ret)
exp = dealwith(exp)
else:
ret = re.findall(r'-?\d+\.?\d*', exp)
sum = 0
for i in ret:
sum += float(i)
return str(sum)
def remove_bracket(new_express):
# 提取括号里面没有其他括号的表达式
while True:
ret = re.search(r'\([^()]+\)', new_express)
if ret:
express_no_breacket = ret.group()
print('匹配到内部不再有括号的值：', express_no_breacket)
ret = cal_express_no_breacket(express_no_breacket)
print(new_express, express_no_breacket, ret)
new_express = new_express.replace(express_no_breacket, ret)
new_express = dealwith(new_express)
print(new_express)
else:
print('表达式中没有括号了:', new_express)
ret = cal_express_no_breacket(new_express)
print(ret)
break
express = '1 - 2 * ( ( 6 0 -3 0 +(-40/5) * (9-2*5/3 + 7 /3*99/4*2998 +10 * 568/14 )) - (-4*3)/ (16-3*2) )'
new_express = express.replace(' ', '')
remove_bracket(new_express)