python基础练习

'''
Created on 2018年7月28日

@author: liupf
'''
print("hello world!")
'''
print("%s%%" % '23')
age = 10
if age >= 18:
    print("your age is", age)
    print("adult")
else:
    print("your age is", age)
    print("teenager")

s = input("birth: ")
birth = int(s)
if birth < 2000:
    print('00前')
else:
    print('00后')
--------------------------

name = [ 'Michael', 'Bob', 'Tracy' ]
scores = [95, 75, 85]
d = {'Michael':95, 'Bob':75, 'Tracy':85}

print(d['Bob'])
d['Bob'] = 99
print(d['Bob'])

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

s = set([1,2,3])
print(s)

s.add(4)
print(s)

s.remove(4)
print(s)

s2 = set([2,3,4])
s3 = s & s2
print(s3)

ss = s | s2
print(ss)

a = ['c', 'b', 'a']
a.sort()
print(a)

a = 'abc'
b = a.replace('a', 'A')
print(b)
print(a.replace('a', 'A'))
print(a)

'''

'''
def my_abs(x):
    if not isinstance(x, (int, float)):
        raise TypeErr("bad operand type")
    if x>=0:
        return x
    else:
        return -x

print(my_abs(-11))

print(my_abs(9))
-----------------------------------------

import math
def move(x, y, step, angle=0):
    nx = x + step * math.cos(angle)
    ny = y - step * math.sin(angle)
    return nx, ny

x, y = move(100, 100, 60, math.pi /6)
print(x, y)

#返回一个turple
r = move(100, 100, 60, math.pi /6)
print(r)


def quadratic(a, b, c):
    delt = b*b-4*a*c
    if delt >= 0:
        sqrt_delt = math.sqrt(b*b-4*a*c)
        return ((-1*b + sqrt_delt)/(2*a) , (-1*b - sqrt_delt)/(2*a))
    else:
        print("复数解")
        return (0,0)

a=2
b=3
c=1

print(quadratic(a,b,c));
--------------------------------------

#位置参数
def power(x):
    return x*x;

def n_power(x, n = 2):
    if not isinstance(x, (int)):
        raise TypeErr("bad operand type")
    s = 1
    while n > 0:
        n = n-1
        s = s*x
    return s

print(n_power(2))
print(n_power(2,10))

def add_end(L=None):
    if L is None:
        L=[]
    L.append('END')
    return L

print(add_end([1,2,3]))
print(add_end())
print(add_end())


#可变参数
#number 被作为一个tuple处理，number 可以是一个list
def calc(*number):
    sum = 0
    for n in number:
        sum = sum + n*n
    return sum

print(calc(1, 2, 3))

#关键字参数
#允许传入任意个参数
def person(name, age, **kw):
    print('name', name, 'age', age, 'other', kw)

person('Michael', 30, city='ab', job='worker')

extra = {'city':'Beijing', 'job':'Engineer'}
person('Jack', 24, city=extra['city'], job=extra['job'])

person('Jessy', 26, **extra)


#命名关键字参数
def person(name, age, **kw):
    if 'city' in kw:
        pass
    if 'job' in kw:
        pass
    print('name:', name, 'age:', age, 'other:', kw)

person('Jack', 24, city='Beijing', addr='Chaoyang', zipcode=123456)


def product(*arg):
    y = 1
    for i in arg:
        y = y*i
    return y

print(product(5))
print(product(5,6))
print(product(5,6,7))
print(product(5,6,7,9))
'''

'''
尾递归是指，在函数返回的时候，调用自身本身，并且，return语句不能包含表达式。
这样，编译器或者解释器就可以把尾递归做优化，使递归本身无论调用多少次，都只
占用一个栈帧，不会出现栈溢出的情况。
'''
'''
def fact(n):
    return fact_iter(n, 1)

def fact_iter(num, product):
    if num == 1:
        return product
    return fact_iter(num-1, num*product)



from tkinter import *
import tkinter.messagebox as messagebox

class Application(Frame):
    def __init__(self, master=None):
        Frame.__init__(self, master)
        self.pack()
        self.createWidgets()

    def createWidgets(self):
        self.nameInput = Entry(self)
        self.nameInput.pack()
        self.alertButton = Button(self, text='Hello', command=self.hello)
        self.alertButton.pack()

    def hello(self):
        name = self.nameInput.get() or 'world'
        messagebox.showinfo('Message', 'Hello, %s' % name)

app = Application()
# 设置窗口标题:
app.master.title('Hello World')
# 主消息循环:
app.mainloop()
------------------------------------------

#汉诺塔 递归
def move(n, a, b, c):
    if n == 1:
        print('move', a, '-->', c)
    else:
        move(n-1, a, c, b)
        move(1, a, b, c)
        move(n-1, b, a, c)

move(4, 'A', 'B', 'C')

L = list(range(100))
L1 = L[:]#复制了一个L对象，由L1指向之

L[0] = 9
print(L[0])
print(L1[0])

print((0,1,2,3,4,)[:3])
-----------------------
'''
#实现trim函数，去除字符串前后的空格 
def trim(s):
    #起始位置
    a = 0
    #结束位置
    b = 0
    for c in s:
        if c.isspace():
            a += 1
        else:
            break

    for c in s:
        if c.isspace():
            b += 1
        else:
            b = 0
    b = len(s) - b
    print(a,b)
    return s[a:b]

#print(trim('   hello   '))
'''''''''

#使用递归
def trim(s):
    if s[:1] == ' ':
        return trim(s[1:])
    elif s[-1:] == ' ':
        return trim(s[:-1])
    else:
        return s


s = '   hello  '
print(trim(s))
------------------------------------

dict = {'a':1, 'b':2, 'c':3}
for key in dict:
    print(key)

from collections import Iterable

a = 123

if( isinstance(a, Iterable)):
    print(a, "is iterable")
    print("%s is iterable" % a)
else:
    print(a, "is not iterable")
    print("%s is not iterable" % a)

-------------------------------------
L = []#[1, 3, 4, 9]

def findMinAndMax(L):
    if not len(L):
        return (None, None)
    max = min = L[0]
    for i in L:
        if (i < min):
            min = i
        if (i > max):
            max = i

    return (min, max)

print(findMinAndMax(L))

print([m + n for m in 'ABC' for n in 'XYZ'])

import os 
print([d for d in os.listdir('.')])

d = {'x':'A', 'y':'B', 'z':'C'}
for v, k in d.items():
    print(k, '=', v)

---------------------------------------------
L1 = ['Hello', 'World', 18, 'Apple', None]
#if条件放到了最后==！
L2 = [s.lower() for s in L1 if(isinstance(s, str))]

print(L2)
---------------------------------------------
g = (x*x for x in range(10))
for n in g:
    print(n)
-------------------------

def fib(max):
    n, a, b = 0, 0, 1
    while n < max:
        print(b)
        a, b = b, a+b

        n = n+1
    return 'done'
print(fib(3))

def f(max):
    n, a, b = 0, 0, 1
    while n < max:
        yield b
        a, b = b, a+b
        n = n+1
    return 'done'

d = f(10)
for i in d:
    print(i)

'''


#杨辉三角
def triangles():
    a=[1]
    while True:
        yield a
        a=[sum(i) for i in zip([0]+a,a+[0])]
n=0
for t in triangles():
    print(t)
    n=n+1
    if n == 10:
        break