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课程简介

Python for Everybody 零基础程序设计（Python 入门）

• This course aims to teach everyone the basics of programming computers using Python. 本课程旨在向所有人传授使用 Python 进行计算机编程的基础知识。
• We cover the basics of how one constructs a program from a series of simple instructions in Python. 我们介绍了如何通过 Python 中的一系列简单指令构建程序的基础知识。
• The course has no pre-requisites and avoids all but the simplest mathematics. Anyone with moderate computer experience should be able to master the materials in this course. 该课程没有任何先决条件，除了最简单的数学之外，避免了所有内容。任何具有中等计算机经验的人都应该能够掌握本课程中的材料。
• This course will cover Chapters 1-5 of the textbook “Python for Everybody”. Once a student completes this course, they will be ready to take more advanced programming courses. 本课程将涵盖《Python for Everyday》教科书的第 1-5 章。学生完成本课程后，他们将准备好学习更高级的编程课程。
• This course covers Python 3.

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coursera

Python for Everybody 零基础程序设计（Python 入门）

Charles Russell Severance
Clinical Professor

个人主页
Twitter

University of Michigan

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课程资源

coursera原版课程视频
coursera原版视频-中英文精校字幕-B站
Dr. Chuck官方翻录版视频-机器翻译字幕-B站

PY4E-课程配套练习
Dr. Chuck Online - 系列课程开源官网

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Quiz 10: Tuples

The tuple is a Python data structure that is like a simple and efficient list.

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单选题（1-11）

1. What is the difference between a Python tuple and Python list?

• Lists are indexed by integers and tuples are indexed by strings
• Tuples can be expanded after they are created and lists cannot
• Lists are mutable and tuples are not mutable
• Lists maintain the order of the items and tuples do not maintain order

2. Which of the following methods are available for both Python lists and Python tuples?

• sort()
• append()
• index()
• reverse()
• pop()

3. What will end up in the variable y after this code is executed?

x , y = 3, 4

• 3
• A two item list
• A dictionary with the key 3 mapped to the value 4
• A two item tuple
• 4

4. In the following Python code, what will end up in the variable y?

x = { 'chuck' : 1 , 'fred' : 42, 'jan': 100}
y = x.items()

• A tuple with three integers
• A list of integers
• A list of tuples
• A list of strings

5. Which of the following tuples is greater than x in the following Python sequence?

x = (5, 1, 3)
if ??? > x :
   ...

• (6, 0, 0)
• (0, 1000, 2000)
• (4, 100, 200)
• (5, 0, 300)

6. What does the following Python code accomplish, assuming the c is a non-empty dictionary?

tmp = list()
for k, v in c.items() :
    tmp.append( (v, k) )

• It computes the average of all of the values in the dictionary
• It computes the largest of all of the values in the dictionary
• It sorts the dictionary based on its key values
• It creates a list of tuples where each tuple is a value, key pair

7. If the variable data is a Python list, how do we sort it in reverse order?

• data = sortrev(data)
• data.sort(reverse=True)
• data.sort.reverse()
• data = data.sort(-1)

8. Using the following tuple, how would you print ‘Wed’?

days = ('Mon', 'Tue', 'Wed', 'Thu', 'Fri', 'Sat', 'Sun')

• print(days{2})
• print[days(2)]
• print(days[1])
• print(days[2])
• print(days(2))
• print(days.get(1,-1))

9. In the following Python loop, why are there two iteration variables (k and v)?

c = {'a':10, 'b':1, 'c':22}
for k, v in c.items() :
    ...

• Because the keys for the dictionary are strings
• Because the items() method in dictionaries returns a list of tuples
• Because for each item we want the previous and current key
• Because there are two items in the dictionary

10. Given that Python lists and Python tuples are quite similar - when might you prefer to use a tuple over a list?

• For a temporary variable that you will use and discard without modifying
• For a list of items that want to use strings as key values instead of integers
• For a list of items you intend to sort in place
• For a list of items that will be extended as new items are found

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编程题

Exercise 10.2

题目：
Write a program to read through the mbox-short.txt and figure out the distribution by hour of the day for each of the messages.
You can pull the hour out from the 'From ’ line by finding the time and then splitting the string a second time using a colon.

From stephen.marquard@uct.ac.za Sat Jan  5 09:14:16 2008

Once you have accumulated the counts for each hour, print out the counts, sorted by hour as shown below.

[Desired Output]

04 3
06 1
07 1
09 2
10 3
11 6
14 1
15 2
16 4
17 2
18 1
19 1

解题代码：

>name = input("Enter file:")
if len(name) < 1:
   name = "mbox-short.txt"
handle = open(name)

d = dict()
for line in handle:
   ls = line.split()
   if line.startswith('From') and len(ls) == 7 :
       lh = ls[5].split(':')
       d[lh[0]] = d.get(lh[0], 0) + 1

lkv = sorted([(k, v) for k, v in d.items()], reverse=False)

for k, v in lkv:
   print(k, v)