02 Python元组字典数据类型 if while for 迭代

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990487026 2015-12-13 14:59:54 博主文章分类：Linux 开发 ©著作权

文章标签 02 Python元组字典数据类型 文章分类 Python 后端开发

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元组

字典类型

数据类型与运算

集合的交集

if while for自动迭代

将两个列表组合成字典

迭代器：列表解析比for 更快的方法对原数值进行选择利用

偏移元素

元组

In [1]: t1= (1,1,2,3) 用括号表示元组

In [2]: t1.count(1) 统计

Out[2]: 2

In [3]: t1.index(3) 索引

Out[3]: 3

In [4]: print t1[2:] 切片

(2, 3)

In [5]: t4='x','y','zy' 也可以省略括号

In [6]: print t4

('x', 'y', 'zy')

In [15]: t4=(1,5,7) 元组相加

In [16]: t3=(2,5,4,9)

In [17]: t4+t3 元组相加

Out[17]: (1, 5, 7, 2, 5, 4,9) 生成的是一个新的元组

In [19]: t4*2 指定重复次数

Out[19]: (1, 5, 7, 1, 5, 7)

In [20]: 5 in t4 判断成员是否存在

Out[20]: True

字典类型（通过键实现存取，无序集合）

In [1]:d1={'a':32,'b':[1,2,3,4,5]}

In [2]: d1['a']

Out[2]: 32

In [3]: d1['b']

Out[3]: [1, 2, 3, 4, 5]

In [6]: d1['b'][:]

In [7]: d1['b'][3:]

Out[7]: [4, 5]

In [8]: len(d1) 获取字典的长度

Out[8]: 2

In [9]: d1['a']=111 修改值后无序存放

In [10]: print d1

{'a': 111, 'b': [1, 2, 3, 4,5]}

In [14]: d2=d1.copy()

In [15]: print d2

{'a': 111, 'b': [1, 2, 3, 4,5]}

In [16]: d2.get('a') 返回值不存在不会抛出异常

Out[16]: 111

In [17]: d1.has_key('a')

Out[17]: True

In [18]: d1.items() 把字典转化为列表

Out[18]: [('a', 111), ('b',[1, 2, 3, 4, 5])]

In [19]: q1,q2=d1.items() 变量解包

In [20]: print q1

('a', 111)

In [21]: print q2

('b', [1, 2, 3, 4, 5])

In [22]: m1,m2={'a':32,'f':54} 保存的是键值

In [23]: print m1

In [24]: print m2

In [28]: print d1

{'a': 111, 'b': [1, 2, 3, 4,5]}

In [25]: d1.keys() 返回键值

Out[25]: ['a', 'b']

In [26]: d1.items() 拆解为列表

Out[26]: [('a', 111), ('b',[1, 2, 3, 4, 5])]

In [27]: d1.values() 返回数值

Out[27]: [111, [1, 2, 3, 4,5]]

In [29]: d1.popitem() 随机弹出键值映射

Out[29]: ('a', 111)

In [30]: d2 = {'a':32,'b':43}键名重复时，会覆盖原来的键值，相当于合并覆盖

In [31]: d3 ={'a':37,'c':63,'f':7546}

In [32]: d2.update(d3)

In [33]: print d2

{'a': 37, 'c': 63, 'b': 43,'f': 7546}

In [39]: i1=d2.iteritems()

In [40]: i1.next()

Out[40]: ('a', 37)

In [41]: i1.next()

Out[41]: ('c', 63)

In [42]: i1.next()

Out[42]: ('b', 43)

In [43]: i2=d2.iterkeys()

In [44]: i2.next() 迭代器

Out[44]: 'a'

In [45]: i2.next()

Out[45]: 'c'

In [46]: zip('123','qwe') 展开功能，不被匹配的就会被舍弃

Out[46]: [('1', 'q'), ('2','w'), ('3', 'e')]

In [47]:zip('123','qwe','222')

Out[47]: [('1', 'q', '2'),('2', 'w', '2'), ('3', 'e', '2')]

In [52]:dict(zip('123','qwe')) 用来创建字典

Out[52]: {'1': 'q', '2': 'w','3': 'e'}

----------------------------------------------------------------

数据类型与运算

n[55]: l1=[8,6,4,6,9,0,45,2]

In [56]: l1.sort()

In [58]: print l1

[0, 2, 4, 6, 6, 8, 9, 45]

In [59]: l1.reverse()

In [60]: print l1

[45, 9, 8, 6, 6, 4, 2, 0]

集合

集合的交集

In [1]: s1=set([1,2,3,4])

In [2]: s2=set([5,6,3,9,94])

In [3]: s1&s2 都一样

In [5]: s1.intersection(s2)

Out[3]: {3}

In [4]: s1|s2

Out[4]: {1, 2, 3, 4, 5, 6, 9,94}

In [7]:s1.symmetric_difference(s2) 显示不同

Out[7]: {1, 2, 4, 5, 6, 9,94}

In [8]: s2.pop() 也支持弹出

Out[8]: 9

In [9]: s2.update(s1) 合并集合

In [10]: print s2

set([1, 2, 3, 4, 5, 6, 94])

In [11]: s1.add(78) 加入数值或字符串

In [12]: print s1

set([1, 2, 3, 4, 78])

In [13]: s1.add('haha')

In [14]: print s1

set([1, 2, 3, 4, 'haha', 78])

import sys 看计数器引用的次数

In [17]:sys.getrefcount(haha)自己也会用一次

Out[17]: 3

In [23]: a1=3.0

In [23]: a2=4.0

In [24]: a2 // a1

Out[24]: 1.0

In [25]: a2 / a1

Out[25]: 1.3333333333333333

In[26]: s1 =('1','3','k')

In[27]: x,v,f=s1 括号可以省略，就是元组

In[28]: print x,v,f

1 3k

In[1]: l1=[1,2,3,4,5]

In[2]: if 2 in l1:

...: print "haha 2 in l1"

...:

haha2 in l1

In[4]: 2 in l1

Out[4]:True

In[5]: x=3

In[6]: y= 5

if判断语句

In [7]: if x>y :

...: print "max = x"

...: else:

...: print "max =y "

...:

max =y

In [18]: if name=="lcl":

print "name = %s" %name

elifname=="hahaha":

print "%s" %name

else:

....: name='lcl'

....:

name = lcl

In [20]: A=1

In [21]: B=3

In [22]: MAX = A if A>Belse B

In [23]: print MAX

whlie 循环

In [24]: u="ww"

In [25]: while u:

....: print u

....: u=u[1:]

....:

.bai

bai

.com

com

In [45]: u="ww"

In [46]: while u:

print u

u=u[:-1]

....:

www.baidu.c

www.baidu.

www.baidu

www.baid

www.bai

www.ba

www.b

www.

www

x=0;y=10

In [35]: x=0

In [36]: while x<y:

print x

x+=1

....:

In [38]: while x<y:

print x,加逗号可以在一行中显示

x+=1

....:

0 1 2 3 4 5 6 7 8 9

In [55]: u="ww"

In [56]: while u:

print u

u=u[:-1]

....: else:

....: print "hahah" 执行完后做一次

....:

www.baidu.c

www.baidu.

www.baidu

www.baid

www.bai

www.ba

www.b

www.

www

hahah

In[83]: l1=[1,2,5,63,89,0]

In[84]: while l1:

....: print l1[0]

....: l1.pop(0)

....:

逆序来显示

In [85]: l1=[1,2,5,63,89,0]

In [86]: while l1:

....: print l1[-1]

....: l1.pop() 默认弹出最后一个

....:

In[96]: x=1

In[97]: l1=[]

In[98]: while x<=100:

l1.append(x)

x+=2

....:

In[102]: print l1

[1,3, 5, 7, 9, 11, 13, 15, 17, 19, 21, 23, 25, 27, 29, 31, 33, 35, 37, 39, 41, 43,45, 47, 49, 51, 53, 55, 57, 59, 61, 63, 65, 67, 69, 71, 73, 75, 77, 79, 81, 83,85, 87, 89, 91, 93, 95, 97, 99]

将两个列表组合成字典

In [103]: d1={}

In [104]: count = 0

In [105]: l1= [0,1,2,3,4,5,6]

In [106]:l2=['sun','mon','tue','wen','thu','fri','sat']

In [108]: while count<len(l1):

.....: d1[l1[count]]= l2[count]

.....: count+=1

.....:

In [109]: print d1

{0: 'sun', 1: 'mon', 2:'tue', 3: 'wen', 4: 'thu', 5: 'fri', 6: 'sat'}

for循环（比while要快）

In [111]: for x in l2: 自动迭代

.....: print x

.....:

sun

mon

tue

wen

thu

fri

sat

生成1到33个数的数列 range(1,34)

sum =0

In [119]: for i in range(1,101): 先在内存生成序列

sum+=i

print sum

----------------------------------------

In [125]: sum =0

In [126]: for i in xrange(1,101): 用一个数就生成一个数，节约空间，合理利用内存

sum+=i

.....:

In [127]: print sum

5050

In[128]: test=[]

In[130]: while True:

.....: x=raw_input("输入一个数")

.....: if x == 'q' or x == 'quit':

.....: break

.....: else:

.....: test.append(x)

In [131]: print test

['3','4', '5', '6', '7', 'f', 'd']

In [132]: d1={'q':122,'d':54324,'t':754,'f3':432}

In [133]: for(k,v)ind1.items(): print k,v

q 122

f3 432

d 54324

t 754

显示奇数项的值

l2=['sun','mon','tue','wen','thu','fri','sat']

for i in range(1,len(l2),2):print l2[i]

mon

wen

fri

挑出

In [138]:l2=['sun','mon','tue','wen','thu','fri','sat']

In [139]:l1=['haha','fd','fds','wen','thu','fri','sat']

In [140]: l3 =[]

In [142]: for i in l2:

if i not in l1:

l3.append(i)

In [143]: print l3

['sun', 'mon', 'tue']

删除别人已存在的

In [144]: l1=['sun','mon','tue','wen','thu','fri','sat']

In [145]: l2=['thu','fri','sat']

In [147]: for i in l2:

if i in l1:

l1.remove(i)

In [148]: print l1

['sun', 'mon', 'tue', 'wen']

--------------------------------------------

迭代器

In [149]:l1=['sun','mon','tue','wen','thu','fri','sat']

In [150]: i1=iter(l1)

In [151]: i1.next()

Out[151]: 'sun'

In [152]: i1.next()

Out[152]: 'mon' 然后抛出异常，不是出错

【列表解析】以第一个为基础，创建新的列表

In [153]: k1=[1,2,3,4,5]

In [154]: k2=[]

In [155]: for i in k1:

.....: k2.append(i**2)

In [157]: print k2

[1, 4, 9, 16, 25]

【比for 更快的方法】

In [158]: k3=[1,3,5,7]

In [159]: k4=[i**3 for i in k3]

In [160]: print k4

[1, 27, 125, 343]

【对原数值进行选择利用】

In [161]: k4=[i**3 for i ink3 if i >3]

In [162]: print k4

[125, 343]

【1到10的平方，再除以2】

In [167]: for i in [i**2 fori in range(1,11)]:

print i/2,

.....:

0 2 4 8 12 18 24 32 40 50

【1到10偶数的平方，再除以2】

In [168]: for i in [i**2 fori in range(2,11,2)]:

print i/2,

.....:

2 8 18 32 50

【获取log后缀的文件名】

In [174]: filelist1=os.listdir('/var/log')

In [175]: filelist2=[i for iin filelist1 if i.endswith('.log') ]

print filelist2

['mysqld.log','anaconda.ifcfg.log', 'anaconda.storage.log', 'dracut.log','anaconda.program.log', 'yum.log', 'anaconda.yum.log', 'Xorg.9.log','boot.log', 'Xorg.0.log', 'anaconda.log', 'wpa_supplicant.log','pm-powersave.log']

【类似于多项式相乘】

In [178]: l1 =[3,5,7,9,67]

In [179]: l2=['a','s','d']

In [180]: l3=[(i,j) for i inl1 for j in l2]

In [182]: print l3

[(3, 'a'), (3, 's'), (3,'d'), (5, 'a'), (5, 's'), (5, 'd'), (7, 'a'), (7, 's'), (7, 'd'), (9, 'a'), (9,'s'), (9, 'd'), (67, 'a'), (67, 's'), (67, 'd')]

【再复杂一点，5不参与运算】

In [1]: l1 =[3,5,7,9,67]

In [2]: l2=['a','s','d']

In [5]: l3=[(i,j) for i in l1for j in l2 if i!=5]

In [6]: print l3

[(3, 'a'), (3, 's'), (3,'d'), (7, 'a'), (7, 's'), (7, 'd'), (9, 'a'), (9, 's'), (9, 'd'), (67, 'a'),(67, 's'), (67, 'd')]

【生成器表达式用小括号】

In[7]: [i**2 for i in range(1,11) ]

Out[7]:[1, 4, 9, 16, 25, 36, 49, 64, 81, 100]

In[8]: h1=(i**2 for i in range(1,11) )

In[9]: h1.next()

Out[9]:1