full-speed-python 习题解答(二)-优快云博客

本文链接：https://blog.youkuaiyun.com/qq_33251995/article/details/83215175

本文深入探讨Python中字符串和列表的基本操作，包括初始化、查找、替换、切片及平均值计算等，通过实例演示如何高效处理数据结构。

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项目地址:网页地址
full-speed-python书籍地址：https://github.com/joaoventura/full-speed-python

3.2. Exercise with strings
1.Initialize the string “abc” on a variable named “s”:
(a) Use a function to get the length of the string.
(b) Write the necessary sequence of operations to transform the string “abc” in
“aaabbbccc”. Suggestion: Use string concatenation and string indexes.

  s='abc'
  print(len(s))
  print('{0}{0}{0}{1}{1}{1}{2}{2}{2}'.format('a','b','c'))
  print(s[0]*3+s[1]*3+s[2]*3)

3
aaabbbccc
aaabbbccc

Initialize the string “aaabbbccc” on a variable named “s”:
(a) Use a function that allows you to find the first occurence of “b” in the string,
and the first occurence of “ccc”.
(b) Use a function that allows you to replace all occurences of “a” to “X”, and
then use the same function to change only the first occurence of “a” to “X”.
```
  s='aaabbbccc'
 print(s.find('b'))
 print(s.find('ccc'))
 print(s.find('a'))
 print(s.replace(s[4],'X'))
 print(s.replace('a','X',1))
```
3
6
0
aaaXXXccc
Xaabbbccc

3.Starting from the string “aaa bbb ccc”, what sequences of operations do you need
to arrive at the following strings? You can find the “replace” function.
(a) “AAA BBB CCC”
(b) “AAA bbb CCC”
```
 s='aaa bbb ccc'
  s=s.upper()
 print(s)
  print(s.replace('B','b'))
```
AAA BBB CCC
AAA bbb CCC

3.3 Exercise with lists
Create a list named “l” with the following values ([1, 4, 9, 10, 23]).
1.Using list slicing get the sublists [4, 9] and [10, 23].
2.Append the value 90 to the end of the list “l”. Check the difference between list
concatenation and the “append” method.
3.Calculate the average value of all values on the list. You can use the “sum” and
“len” functions.
4.Remove the sublist [4, 9].
```
 l = [1,4,9,10,23]
 print(l[1:3])
 print(l[3:5])
 l+[90]
 print('l concatenation 90 is',l)
 l.append(90)
 print('l append 90 is',l)
 ave = sum(l)/len(l)
 print('average is',ave)
 l.remove(4)
 l.remove(9)
 print('l remove [4,9] is',l)
```
[4, 9]
[10, 23]
l concatenation 90 is [1, 4, 9, 10, 23]
l append 90 is [1, 4, 9, 10, 23, 90]
average is 22.833333333333332
l remove [4,9] is [1, 10, 23, 90]