python基础(List，Dictionary，Random，循环，Lambda，Tumple)

一.List

#coding=utf-8
xx = [8, 2, 4, 5, 6]
xx.append(7)
print xx
print xx[:3]
print xx[3:]
print xx.index(4)
xx.insert(3, 3)
print xx
xx.sort()
print xx
xx.remove(2)
print xx
xx.pop(2)
print xx
del(xx[1])
print xx

m = [1, 2, 3]
n = [4, 5, 6]
m += n
print m
m = [1, 2, 3]
m.extend(n)
print m
letters = ['a', 'b', 'c', 'd']
print '---'.join(letters)
print ["o"] * 5

a = [5, 4, 3, 2, 1]
print sorted(a) #1, 2, 3, 4, 5
print a#5, 4, 3, 2, 1

 

print xrange(3, 11, 2)
print list(xrange(3, 11, 2))

 

xrange 用法与 range 完全相同，所不同的是生成的不是一个list对象，而是一个生成器

a = range(0,100)
print type(a)
print a
print a[0], a[1]

a = xrange(0,100)
print type(a)
print a
print a[0], a[1]

a = [1,132,0.432]
print help(a.sort) #sort(cmp=None, key=None, reverse=False)
a.sort(reverse=True)
print a
a = ['ab', 'abc', 'a']
a.sort(key=len)
print a

lst = range(1, 11)
print lst[::2] #[1, 3, 5, 7, 9]

letters = ['a', 'b', 'c']
print letters[::-1] #['c', 'b', 'a']
print letters[-2:] #['b', 'c']

 

二.Dictionary

 

menu = {}
menu['ChickenAlfredo'] = 14.5
menu['Spam'] = 2.5
menu['American'] = 2.5
menu['China'] = 2.5
print menu
print menu.items()
print menu.keys()
print menu.values()

del menu['China']
print menu

inventory = {'g':500, 'p':['flint', 'twine']}

lloyd = {'a':1, 'c':2, 'b':3}
print lloyd.get('a')

keys should hashable 生存期内可变的对象不可以hash（列表，字典，集合）

字典keys无顺序

 

 

#coding=utf-8
xx = [['a' , 1], ['b' , 2]]
yy = [('a' , 1), ('b' , 2)]
print dict(xx) #{'a': 1, 'b': 2}
print dict(yy) #{'a': 1, 'b': 2}
print dict(a = 1, b = 2) #{'a': 1, 'b': 2}

a = {}.fromkeys(('a', 'b', 'c', 'd'), 3000)
print a #{'a': 3000, 'c': 3000, 'b': 3000, 'd': 3000}

del xx #删除字典

template = 'abc %(a)d, %(b)d'
print template%dict(yy) #abc 1, 2

a = ['a', 'b', 'c']
b = [1, 2, 3]
c = dict(zip(a, b)) #{'a': 1, 'c': 3, 'b': 2}

 

 

 

二.Random

import random
random.randint(0, 5) #0, 1, 2, 3, 4, 5
random.randrange(0, 5, 1) #0, 1, 2, 3, 4

 

三.循环

 

count = 0
while count < 10
    count += 1

while count < 3:
    pass
else:
    pass

while count != 'y' and count != 5:
    count -= 1

for i in range(20):
    print i #0-19

thing = "Spam!"
for c in thing:
    print c

d = {'a' : 1, 'b' : 2}
for key in d:
    print d[key]

 

 

list = ['a', 'b', 'c', 'd']
for i, j in enumerate(list):
    print i + 1, j

m = [3, 5, 7, 9]
n = [2, 4, 6, 8, 10, 12, 14]
print zip(m, n)
for a, b in zip(m , n):
    if a > b:
        print a
    else:
        print b

五.Lambda，filter，map，reduce

 

#coding=utf-8
bythree = lambda x: x % 3 == 0
print bythree(9)#True

add = lambda x, y: x+y
print add(3, 4) #7

myList = [3, 6, 9, 12, 11, 10]
print filter(bythree, myList)
"""
对myList中每项依次执行function将结果为true的item组成一个List，String，Tuple（取决于myList类型）
filter(function, sequence)
[3, 6, 9, 12]
"""

print map(lambda x:x**2, range(1,11))
"""
对sequence中每项依次执行function将结果返回的item组成一个List
map(function, sequence)
[1, 4, 9, 16, 25, 36, 49, 64, 81, 100]
"""

print reduce(add, range(1, 11), 20)
"""
对sequence中每项顺序迭代调用
reduce(function, sequence, starting_value)
1+2+3+4+5+6+7+8+9+10+20=75
"""

 二.Tumple

#coding=utf-8
t = ('a', 'b', 'c', 'd', 'e')
print type(t) #<type 'tuple'>
print t #('a', 'b', 'c', 'd', 'e')
print (0, 1, 2) < (0, 3, 4) #True
print (0, 1, 2000000) < (0, 3, 4)#True
"""
比较运算符适用于元组和其它序列， Python从每个序列的第一个元素开始比较。 如果它们相等， 继续比较下一个元素， 以此
类推， 直到找到不同的元素。 找到不同元素之后， 随后的元素就不再考虑了 （ 即便它们真得很大）
"""
t = (3, 2, 1)
(x, y, z) = t
print x, y, z #3, 2, 1
a = 1
b = 2
b, a = a, b
print a, b # 2 1

dic = {'a':1, 'b':2, t:3}
print dic #{'a': 1, 'b': 2, (3, 2, 1): 3}