# 1 编写 tail -f a.txt |grep 'error' |grep '404'命令，周一默写 # import time # def tail(filepath,encoding='utf-8'): # with open(filepath,encoding=encoding)as f: # f.seek(0,2) # while True: # line=f.readline() # if line: # yield line # else: # time.sleep(0.5) # def grep(lines,pattern): # for line in lines: # if pattern in line: # # print(line) # yield line # g=tail('a.txt') # g2=grep(g,'error') # g3=grep(g2,'404') # for i in g3: # print(i) # 2 文件a.txt内容 # apple 10 3 # tesla 100000 1 # mac 3000 2 # lenovo 30000 3 # chicken 10 3 # with open('a.txt','w',encoding='utf-8')as f: # f.write('apple 10 3 tesla 100000 1 mac 3000 2 lenovo 30000 3 chicken 10 3') # 要求使用列表解析，从文件a.txt中取出每一行，做成下述格式 # [{‘name’:'apple','price':10,'count':3},{...},{...},...] # with open('a.txt', 'r', encoding='utf-8')as f: # print([{'name':line.strip().split()[0],'price':line.strip().split()[1],'count':line.strip().split()[2]} for line in f]) # for i in [{'name':line.strip().split()[0],'price':line.strip().split()[1],'count':line.strip().split()[2]} for line in f]: # print(i) # 3 格式与2一样，但只保留价格大于1000的商品信息 # with open('a.txt',encoding='utf-8')as f: # for i in [{'name':line.strip().split()[0],'price':line.strip().split()[1],'count':line.strip().split()[2]} for line in f]: # if int(i['price'])>1000: # print(i) # 4 周末大作业（见图）： # 只实现作业要求的查询功能 # 增加，删除，修改功能为选做题