Python内置函数
Python内置了很多函数，他们都是一个个的.py文件，在python的安装目录可以找到。
列出一些常用的
列出一些常用的
- abs, max, min, len, divmod, pow, round, callable,
- isinstance, cmp, range, xrange, type, id, int()
- list(), tuple(), hex(), oct(), chr(), ord(), long()
- numList = [1, 2]
- if type(numList) == type([]):
- print "It is a list"
- if isinstance(numList, list): # the same as above, return true
- print "It is a list"
- for i in range(1, 10001) # will create a 10000 list, and cost memory
- for i in xrange(1, 10001)# do not create such a list, no memory is cost
- str = 'hello world'
- str.capitalize() # 'Hello World', first letter transfer to big
- str.replace("hello", "good") # 'good world'
- ip = "192.168.1.123"
- ip.split('.') # return ['192', '168', '1', '123']
- help(str.split)
- import string
- str = 'hello world'
- string.replace(str, "hello", "good") # 'good world'
- len, max, min
-
filter(function or none, sequence)
- def fun(x):
- if x > 5:
- return True
- numList = [1, 2, 6, 7]
- filter(fun, numList) # get [6, 7], if fun return True, retain the element, otherwise delete it
- filter(lambda x : x % 2 == 0, numList)
-
zip()
- name = ["me", "you"]
- age = [25, 26]
- tel = ["123", "234"]
- zip(name, age, tel) # return a list: [('me', 25, '123'), ('you', 26, '234')]
-
map()
- map(None, name, age, tel) # also return a list: [('me', 25, '123'), ('you', 26, '234')]
- test = ["hello1", "hello2", "hello3"]
- zip(name, age, tel, test) # return [('me', 25, '123', 'hello1'), ('you', 26, '234', 'hello2')]
- map(None, name, age, tel, test) # return [('me', 25, '123', 'hello1'), ('you', 26, '234', 'hello2'), (None, None, None, 'hello3')]
- a = [1, 3, 5]
- b = [2, 4, 6]
- def mul(x, y):
- return x*y
- map(mul, a, b) # return [2, 12, 30]
-
reduce()
- reduce(lambda x, y: x+y, [1, 2, 3, 4, 5]) # return ((((1+2)+3)+4)+5)
