【python】第五周-复习Python内置函数

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)