pylearn.md

##Function and Method ###functions map(str, [1, 2, 3, 4, 5, 6, 7, 8, 9]) reduce(max, [1, 3, 5, 9, 7]) filter(lambda x: x and x.strip(), ['A', '', 'B', None, 'C', ' ']) sorted([36, 5, 12, 9, 21], reverce = True) ###compair [x * x for x in [1, 2, 3, 4]] better than: map(lambda x: x * x, [1, 2, 3, 4])

decorator

def decorator(func):
    def wrapper():
        before_func()
        func()
        after_func()
        return
    return wrapper

@decorator
def foo():
    pass

###functools import functools int2 = functools.partial(int, base = 2) ###future from future import division, unicode_literals ##Object Oriented Programming ###class class Student(object):

    def __init__(self, name, score):
        self.name = name
        self.score = score

    def print_score(self):
        print '%s,%s' % (self.name, self.score)

lisa = Student('Lisa', 60)
bart = Student('bart', 100)
print '%s,%s' % (lisa.name, lisa.score)
bart.print_score()

###private and encapsulation class Student(object):

    def __init__(self, name, score):
        self.__name = name
        self.__score = score

    def print_score(self):
        print '%s: %s' % (self.__name, self.__score)

    def get_name(self):
    return self.__name

    def get_score(self):
        return self.__score

    def set_score(self, score):
        if 0 <= score <= 100:
            self.__score = score
        else:
            raise ValueError('bad score')

nick = Student('Nick', 90)
nick.print_score()

print nick.get_score()
print nick.get_name()

nick.set_score(80)
nick.print_score()

print nick._Student__name
print fox('fox',70)._Student__name

print nick.__score  # will not work
nick.__score = 'nick'  # will not work

##inheritance and polymorphism

• The subclass inherits the methods and interface from the abstract class, and it provides details for the abstract method by overriding it.
• date type is class

class Animal(object):

    def run(self):
        print 'Animal is running...'


class Dog(Animal):

    def run(self):
        print 'Dog is running...'

    def eat(self):
        print 'Dog is eating...'


class Cat(Animal):

    def run(self):
        print 'Cat is running...'

dog = Dog()
cat = Cat()
dog.run()
cat.run()
dog.eat()

print isinstance(dog, Dog)
print isinstance(cat, Animal)
print isinstance(Animal, Dog)


def run_twice(animal):
    animal.run()
    animal.run()

run_twice(Dog())
run_twice(Cat())
run_twice(Animal())

###get object information import types

print type('abc') == type('123')
print isinstance(123,int)
print type(type(None)) == types.TypeType
print dir(u'abc') == dir(unicode)

###from function to object print len('abc') print 'abc'.len ###attribute class MyObject(object):

    def __init__(self):
        self.x = 3

    def power(self):
        return self.x * self.y

obj = MyObject()
print hasattr(obj, 'x')
print hasattr(obj, 'y')
print hasattr(obj, 'power')

setattr(obj, 'y', 4)
print hasattr(obj, "y")

print obj.y
print getattr(obj, 'y')
print getattr(obj, 'z', '404 not find')

print getattr(obj, 'power')()  # ugly
print obj.power()  # better