第七章、 数据结构

1、第七章、 数据结构python中有三种内建的数据结构 列表、元组和字典。 1) lists列表 , 列表是序列的一种 shoplist = 'apple', 'carrot', 'banana' print shoplist 'apple', 'carrot', 'banana' shoplist.append('orange') 末尾加入一个 print shoplist 'apple', 'carrot', 'banana', &#

2、39;orange' shoplist.insert(2, 'flint') 指定位置插入 print shoplist 'apple', 'carrot', 'flint', 'banana', 'orange' shoplist.reverse() 反转 print shoplist 'orange', 'banana', 'flint', 'carrot', 'apple' shoplist.pop() 默

3、认从末尾删除 print shoplist 'orange', 'banana', 'flint', 'carrot' shoplist.() 正向排序 print shoplist 'banana', 'carrot', 'flint', 'orange' del shoplist1 指定位置删除,等于shoplist.pop(1) print shoplist 'banana', 'flint', 'orange'

4、shoplist.tend('database', 'egg') 末尾加入多个 print shoplist 'banana', 'flint', 'orange', 'database', 'egg' shoplist.remove('banana') 删除指定项 print shoplist 'flint', 'orange', 'database', 'egg' 通过help(list)获得完整的学

5、问。 列表解析表达式 从一个已有的列表导出一个新的列表。 vec = 2, 4, 6 print (3 * x for x in vec) generator object gen at 0x00e7d300 print list(3 * x for x in vec) 6, 12, 18 print 3 * x for x in vec 6, 12, 18 print 3 * x for x in vec if x 3 12, 18 print 3 * x for x in vec if x 2 print x, x*2 for x in vec 2, 4, 4, 16, 6, 36 m =

6、 1, 2, 3, 4, 5, 6, 7, 8, 9 print row1 for row in m 2, 5, 8 print row1 for row in m if row1 % 2 = 0 2, 8 print x + y for x in 'abc' for y in 'mn' 'am', 'an', 'bm', 'bn', 'cm', 'cn' 处理大型矩阵用法开源numpy系统 nesting嵌套 m = 1, 2, 3, 4, 5, 6, 7, 8,

7、9 print m 1, 2, 3, 4, 5, 6, 7, 8, 9 print m0 1, 2, 3 print m12 6 列表解析 list(map(m, m) 6, 15, 24 sum(row) for row in m (24, 6, 15) x: ord(x) for x in 'spabm' 'a': 97, 'p': 112, 's': 115, 'b': 98, 'm': 109 索引操作符 索引操作符,下标操作,从0开头,支持反向索引,从-1开头 sp = 'a

8、9;, 'b', 'c', 'd' sp0, sp1, sp2, sp3 ('a', 'b', 'c', 'd') sp-4, sp-3, sp-2, sp-1 ('a', 'b', 'c', 'd') name = 'swaroop' len(name) 7 name-1 'p' namelen(name) - 1 'p' 切片操作符xi:j 切片(slice)操作符,序

9、列名跟方括号,方括号中有一对可选的数字，并用冒号分割。数是可选的，而冒号是必需的。 xi:j,取出在x中从偏移为i,直到但不包括j的内容 shoplist = 'a', 'b', 'c', 'd' shoplist1:3 'b', 'c' shoplist2: 'c', 'd' shoplist1:-1 'b', 'c' shoplist: 'a', 'b', 'c', 'd

10、9; name = 'swaroop' name1:3 wa,不包括r! name2: aroop name1:-1 waroo name: swaroop name * 2 swaroopswaroop 三元切片操作符xi:j:k xi:j = xi:j:1 s = "abefghijklmn" print s1:10:2 bhj print s:2 acegikm print s:-2 nljhfdb 参考 shoplist = 'apple', 'mango', 'carrot', 'banana

11、' mylist = shoplist mylist is just another name pointing to the same object! del shoplist0 print shoplist 'mango', 'carrot', 'banana' print mylist 'mango', 'carrot', 'banana' mylist = shoplist: make a copy by doing a full slice del mylist0 remove f

12、irst item print shoplist 'mango', 'carrot', 'banana' print mylist 'carrot', 'banana' 假如要复制列表或者序列或者对象，那么你必需用法切片操作符来取得拷贝。记住列表的赋值语句不创建拷贝 浅拷贝深拷贝 浅拷贝(1)彻低切片操作:;(2)利用工厂函数,如list(),dict();(3)用法copy模块的copy函数 深拷贝(1)用法copy模块的deepcopy()函数 模拟堆栈 stack = def pushit(): stack.

13、append(raw_input("enter new sing:").strip() def popit(): if len(stack) = 0: print 'can not pop from an empty stack!' ee: print 'remov ', stack-1, '' stack.pop() def viewstack(): print stack cmds = 'u':pushit, 'o':popit, 'v':viewstack def show

14、menu(): pr = """p(u)sh p(o)p (v)iew (q)uit enter choice:""" while true: while true: try: choice = raw_input(pr).strip()0.lower() except (eoferror, keyboardinterrupt, indexerror): choice = 'q' print 'nyou picked: %s' %choice if choice not in 'uovq'

15、;: print 'inval option, try again' else: break if choice = 'q': break cmdschoice() if _name_ = '_main_': showmenu() 2) tuples元组(,) 元组是不行变的 即不能修改。元组通过圆括号中用逗号分割的项目定义。 zoo = ('w', 'e', 'p') new_zoo = ('m', 'd', zoo) print zoo ('w',

16、 'e', 'p') print new_zoo ('m', 'd', ('w', 'e', 'p') print new_zoo2 ('w', 'e', 'p') print new_zoo22 p new_zoo1 = 'x' typeerror: 'tuple' object does not support item assignment 元组最通常的使用是用在打印语句中 age = 22 name = 'swaroop' print '%s is %d years old' % (name, age) print 'why is %s playing with that python?' % name print语句用法跟着%符号的项目元组的字符串。定制输出满足某种特定的格式。定制可以是%s表示字符串或%d表示整数。 3) dictionaries字典k:v 键值对：d = key1 : value1, key2 : value2 rec