【题解】Assignment 9.4 (Python Data Structures)

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我是靠谱客的博主高高冬天，最近开发中收集的这篇文章主要介绍【题解】Assignment 9.4 (Python Data Structures)，觉得挺不错的，现在分享给大家，希望可以做个参考。

概述

吐槽：还是没听课，然后被数据和系统坑了好久= =

9.4 Write a program to read through the mbox-short.txt and figure out who has sent the greatest number of mail messages. The program looks for 'From ' lines and takes the second word of those lines as the person who sent the mail. The program creates a Python dictionary that maps the sender's mail address to a count of the number of times they appear in the file. After the dictionary is produced, the program reads through the dictionary using a maximum loop to find the most prolific committer.

You can download the sample data at https://www.py4e.com/code3/mbox-short.txt

文件太长了，点上面链接看吧= =

我的程序：

name = input("Enter file:")
if len(name) < 1 : name = "mbox-short.txt"
handle = open(name) #到此为止都是题目给的一部分代码

dic = dict()
maxvalue = 0
maxkey = ''
content = ''

for line in handle:
if(line.startswith("From: ")):
lst = line.rstrip().split(' ')
dic.update({lst[1]:0})
content += line.rstrip()

for key in dic.keys():
dic[key] = content.count(key)
if(dic[key] > maxvalue):
maxvalue = dic[key]
maxkey = key

print(maxkey + ' ' + str(maxvalue))

输出：

cwen@iupui.edu 5

我想说的：

1，这个题坑在里面有句话叫 a Python dictionary that maps the sender's mail address to a count of the number of times they appear in the file ，但是答案给出的不是文件中出现的总次数，认真读题发现是求发送邮件最多的人和次数，所以要小心 content 并不是 handle.read() 。

2，题目上说是From开头的，我把 line.startswith("From") 替换上去则会发现答案是10，不是5，所以很坑哦，仔细看一下文件发现改成 line.startswith("From: ") 就过了。

3，因为需要提交到他的oj，然而里面并没有实现 dict.fromkeys(seq) 的功能（https://www.runoob.com/python/att-dictionary-fromkeys.html），所以无奈只能用 dict1.update(dict2) 来实现（https://www.runoob.com/python/att-dictionary-update.html）。

4，str.count(sub) 真是个好东西（https://www.runoob.com/python/att-string-count.html）。

5，Python中的字符串连接不会像Java一样自动调用toString()，所以要写成str(xxx)，注意报错信息就能改对了，只是提个醒咯。