练习1

1.1) 将 “123” 转换成整数

In [6]: a = "123"

In [7]: b=int(a)

In [8]: type(b)
Out[8]: int  

1.2) 将 “9999999999999999999” 转换成长整数

In [10]: c = "9999999999999999999"

In [11]: type(c)
Out[11]: str

In [12]: d = long(c)

In [13]: type(d)
Out[13]: long

In [14]: d
Out[14]: 9999999999999999999L

1.3) 将 “3.1415926” 转换成一个浮点数

In [15]: e = "3.1415926"

In [16]: f = float(e)

In [17]: f
Out[17]: 3.1415926

In [18]: type(f)
Out[18]: float

1.4) 按要求操作字符串

现有以下字符串
字符串1：" abc deFGh&ijkl opq mnrst((uvwxyz "
字符串2：" ABC#DEF GH%IJ MNOPQ KLRS&&TUVWX(&YZ "
使用字符串的各种方法转换成如下方式
ABCDEFGHIJKLMNOPQRSTUVWXYZzyxwvutsrqponmlkjihgfedcba

In [1]: s1 = "   abc  deFGh&*ijkl opq mnrst((uvwxyz   "

In [2]: s2 = "   ABC#DEF  GH%IJ MNOPQ KLRS&&TUVWX(*&YZ   "

In [3]: t1 = []

In [4]: t2 = []

In [5]: x = ""

In [6]: for a in s1.lower():
   ...:     if a.isalpha():
   ...:         t1.append(a)
   ...:

In [7]: t1.sort()

In [8]: t1.reverse()

In [10]: for a in s2:
    ...:     if a.isalpha():
    ...:         t2.append(a)
    ...:

In [11]: t2.sort()

In [12]: for a in t2:
    ...:     x += a
    ...:

In [13]: for a in t1:
    ...:     x += a
    ...:

In [14]: x
Out[14]: 'ABCDEFGHIJKLMNOPQRSTUVWXYZzyxwvutsrqponmlkjihgfedcba'

练习2

现有列表
list1 = ['XXXX', 'b', 3, 'c', '&', 'a', 3, '3', 3, 'aa', '3', 'XXXX']
list2 = ['e', 'f', 'g']
要求对其做以下操作：

1. 取出 ‘XXXX’ 中间的部分，形成一个新的列表list3

In [1]: list1 = ['XXXX', 'b', 3, 'c', '&', 'a', 3, '3', 3, 'aa', '3', 'XXXX']

In [2]: list2 = ['e', 'f', 'g']

In [3]: list3 = list1

In [4]: list3.pop(0)
Out[4]: 'XXXX'

In [5]: list3.pop()
Out[5]: 'XXXX'

In [6]: list3
Out[6]: ['b', 3, 'c', '&', 'a', 3, '3', 3, 'aa', '3']

2. 对list3 做一下几部操作

1）删除特殊符号

In [6]: list3
Out[6]: ['b', 3, 'c', '&', 'a', 3, '3', 3, 'aa', '3']

In [8]: list3.pop(3)
Out[8]: '&'

In [9]: list3
Out[9]: ['b', 3, 'c', 'a', 3, '3', 3, 'aa', '3']

2）统计 3 在list3中出现的次数

In [11]: list3.count(3)
Out[11]: 3

In [12]: list3.count('3')
Out[12]: 2

3）用最简短的代码去除list3中 26个字母以外的元素(要求只能对list3操作)

In [64]: list3 = ['b', 3, 'c', 'a', 3, '3', 3, 'aa', '3']

In [65]: [ i for i in list3 if str(i).isalpha() ]
Out[65]: ['b', 'c', 'a', 'aa']

4）对list3排序

In [66]: list3
Out[66]: ['b', 3, 'c', 'a', 3, '3', 3, 'aa', '3']

In [67]: list3.sort()

In [68]: list3
Out[68]: [3, 3, 3, '3', '3', 'a', 'aa', 'b', 'c']

5）在末尾追加'd',并把list2追加到list3

In [80]: list3.append('d')

In [82]: list3.append(list2)

In [83]: list3
Out[83]: [3, 3, 3, '3', '3', 'a', 'aa', 'b', 'c', 'd', ['e', 'f', 'g']]

练习3

现有两个变量
a = ('h',)
b = ('h')
1）将a和b分别追加到上一题的list3中，观察有什么区别

In [84]: a = ('h',)
    ...: b = ('h')
    ...: 

In [85]: a
Out[85]: ('h',)

In [86]: b
Out[86]: 'h'

In [87]: list3
Out[87]: [3, 3, 3, '3', '3', 'a', 'aa', 'b', 'c', 'd', ['e', 'f', 'g']]

In [88]: list3.append(a)

In [89]: list3
Out[89]: [3, 3, 3, '3', '3', 'a', 'aa', 'b', 'c', 'd', ['e', 'f', 'g'], ('h',)]

In [90]: list3 = [3, 3, 3, '3', '3', 'a', 'aa', 'b', 'c', 'd', ['e', 'f', 'g']]

In [91]: list3.append(b)

In [92]: list3
Out[92]: [3, 3, 3, '3', '3', 'a', 'aa', 'b', 'c', 'd', ['e', 'f', 'g'], 'h']

2）将1生成的list3转换成元组(扩展：自己搜索方法)

In [92]: list3
Out[92]: [3, 3, 3, '3', '3', 'a', 'aa', 'b', 'c', 'd', ['e', 'f', 'g'], 'h']

In [93]: tuple(list3)
Out[93]: (3, 3, 3, '3', '3', 'a', 'aa', 'b', 'c', 'd', ['e', 'f', 'g'], 'h')

In [94]: list3 = [3, 3, 3, '3', '3', 'a', 'aa', 'b', 'c', 'd', ['e', 'f', 'g'], ('h',)]

In [95]: tuple(list3)
Out[95]: (3, 3, 3, '3', '3', 'a', 'aa', 'b', 'c', 'd', ['e', 'f', 'g'], ('h',))

3）打印出只有一个元素'h'的元组，在2中生成的元组中的索引

In [96]: tuple(list3).index(('h',))
Out[96]: 11