Azza's Blog

>>> x = int(input("Please enter an integer: "))

Please enter an integer: 42

>>> if x < 0:

...      x = 0

...      print('Negative changed to zero')

... elif x == 0:

...      print('Zero')

... elif x == 1:

...      print('Single')

... else:

...      print('More')

...

More

>>> # Measure some strings:

... words = ['cat', 'window', 'defenestrate']

>>> for w in words:

...     print(w, len(w))

...

cat 3

window 6

defenestrate 12

>>> for w in words[:]:  # Loop over a slice copy of the entire list.

...     if len(w) > 6:

...         words.insert(0, w)

...

>>> words

['defenestrate', 'cat', 'window', 'defenestrate']

>>> for i in range(5):

...     print(i)

...

0

1

2

3

4

>>> a = ['Mary', 'had', 'a', 'little', 'lamb']

>>> for i in range(len(a)):

...     print(i, a[i])

...

0 Mary

1 had

2 a

3 little

4 lamb

>>> print(range(10))

range(0, 10)

>>> list(range(5))

[0, 1, 2, 3, 4]

>>> for n in range(2, 10):

...     for x in range(2, n):

...         if n % x == 0:

...             print(n, 'equals', x, '*', n//x)

...             break

...     else:

...         # loop fell through without finding a factor

...         print(n, 'is a prime number')

...

2 is a prime number

3 is a prime number

4 equals 2 * 2

5 is a prime number

6 equals 2 * 3

7 is a prime number

8 equals 2 * 4

9 equals 3 * 3

>>> class MyEmptyClass:

...     pass

...

>>> def initlog(*args):

...     pass   # Remember to implement this!

...

>>> def fib(n):    # write Fibonacci series up to n

...     """Print a Fibonacci series up to n."""

...     a, b = 0, 1

...     while a < n:

...         print(a, end=' ')

...         a, b = b, a+b

...     print()

...

>>> # Now call the function we just defined:

... fib(2000)

0 1 1 2 3 5 8 13 21 34 55 89 144 233 377 610 987 1597

>>> a=10

>>> def f():

a=20

>>> print (a)

10

>>> f()

>>> print (a)

10

>>> def f():

    global a

a=20

>>> print (a)

10

>>> f()

>>> print (a)

20

>>> a=[10,20,30]

>>> def f(l):

l[0]=50

>>> print(a)

[10, 20, 30]

>>> f(a)

>>> print(a)

[50, 20, 30]

>>> fib

<function fib at 10042ed0>

>>> f = fib

>>> f(100)

0 1 1 2 3 5 8 13 21 34 55 89

>>> def fib2(n): # return Fibonacci series up to n

...     """Return a list containing the Fibonacci series up to n."""

...     result = []

...     a, b = 0, 1

...     while a < n:

...         result.append(a)    # see below

...         a, b = b, a+b

...     return result

...

>>> f100 = fib2(100)    # call it

>>> f100                # write the result

[0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89]

>>> def f():

pass

>>> print (f())

None

def ask_ok(prompt, retries=4, complaint='Yes or no, please!'):

    while True:

        ok = input(prompt)

        if ok in ('y', 'ye', 'yes'):

            return True

        if ok in ('n', 'no', 'nop', 'nope'):

            return False

        retries = retries - 1

        if retries < 0:

            raise IOError('refusenik user')

        print(complaint)

ask_ok('Do you really want to quit?')

ask_ok('OK to overwrite the file?', 2)

ask_ok('OK to overwrite the file?', 2, 'Come on, only yes or no!')

i = 5

def f(arg=i):

    print(arg)

i = 6

f()

def f(a, L=[]):

    L.append(a)

    return L

print(f(1))

print(f(2))

print(f(3))

[1]

[1, 2]

[1, 2, 3]

def f(a, L=None):

    if L is None:

        L = []

    L.append(a)

    return L

def parrot(voltage, state='a stiff', action='voom', type='Norwegian Blue'):

    print("-- This parrot wouldn't", action, end=' ')

    print("if you put", voltage, "volts through it.")

    print("-- Lovely plumage, the", type)

    print("-- It's", state, "!")

parrot(1000)                                          # 1 positional argument

parrot(voltage=1000)                                  # 1 keyword argument

parrot(voltage=1000000, action='VOOOOOM')             # 2 keyword arguments

parrot(action='VOOOOOM', voltage=1000000)             # 2 keyword arguments

parrot('a million', 'bereft of life', 'jump')         # 3 positional arguments

parrot('a thousand', state='pushing up the daisies')  # 1 positional, 1 keyword

def cheeseshop(kind, *arguments, **keywords):

    print("-- Do you have any", kind, "?")

    print("-- I'm sorry, we're all out of", kind)

    for arg in arguments:

        print(arg)

    print("-" * 40)

    keys = sorted(keywords.keys())

    for kw in keys:

        print(kw, ":", keywords[kw])

cheeseshop("Limburger", "It's very runny, sir.",

           "It's really very, VERY runny, sir.",

           shopkeeper="Michael Palin",

           client="John Cleese",

           sketch="Cheese Shop Sketch")

위의 실행 결과는 아래와 같다.

-- Do you have any Limburger ?

-- I'm sorry, we're all out of Limburger

It's very runny, sir.

It's really very, VERY runny, sir.

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

client : John Cleese

shopkeeper : Michael Palin

sketch : Cheese Shop Sketch

def write_multiple_items(file, separator, *args):

    file.write(separator.join(args))

>>> def concat(*args, sep="/"):

...    return sep.join(args)

...

>>> concat("earth", "mars", "venus")

'earth/mars/venus'

>>> concat("earth", "mars", "venus", sep=".")

'earth.mars.venus'

>>> list(range(3, 6))            # normal call with separate arguments

[3, 4, 5]

>>> args = [3, 6]

>>> list(range(*args))            # call with arguments unpacked from a list

[3, 4, 5]

>>> def parrot(voltage, state='a stiff', action='voom'):

...     print("-- This parrot wouldn't", action, end=' ')

...     print("if you put", voltage, "volts through it.", end=' ')

...     print("E's", state, "!")

...

>>> d = {"voltage": "four million", "state": "bleedin' demised", "action": "VOOM"}

>>> parrot(**d)

-- This parrot wouldn't VOOM if you put four million volts through it. E's bleedin' demised !

>>> def make_incrementor(n):

...     return lambda x: x + n

...

>>> f = make_incrementor(42)

>>> f(0)

42

>>> f(1)

43

>>> f = lambda a,b:a+b

>>> f(10,20)

30

>>> def my_function():

...     """Do nothing, but document it.

...

...     No, really, it doesn't do anything.

...     """

...     pass

...

>>> print(my_function.__doc__)

Do nothing, but document it.

    No, really, it doesn't do anything.

- 4-space 들여쓰기를 사용하라. tab은 사용하지 말것.

  4 spaces는 더 적은 들여쓰기와 더 큰 들여쓰기의 적절한 타협점이다.

  tab은 혼란을 야기할 수 있으니 사용하지 않는 것이 좋다.

- 한 줄이 79 문자를 넘지 않도록 줄을 나누라.

  이것은 작은 화면을 가진 유저를 위한 것이고,

  더 큰 화면에서 여러 코드 파일을 동시에 볼 수 있게 해 준다.

- 함수와 클래스 그리고 함수 내부의 논리적 코드 블럭을 나누기 위해

  빈 줄을 사용하라.

- 가능하다면, 주석은 해당 코드와 같은 라인에 두라.

- docstrings를 사용하라.

- 연산자 앞뒤와 콤마 뒤에는 공백을 두라. 하지만 괄호 바로 안쪽은 붙여쓰라.

  a = f(1, 2) + g(3, 4)

- class 이름은 CamelCase 형태로, 함수는 lower_case_with_underscores 형태로 쓰라.

  class methon 의 첫 번째 argument의 이름은 항상 self 를 사용하라.

- 소스 파일의 인코딩은 UTF-8을 사용하라. 여의치 않다면 ASCII 도 잘 동작할 것이다.

- 마찬가지로, 식별자로 non-ASCII 문자를 사용하지 마라.

#! /usr/bin/env python3.3

# -*- coding: cp-949 -*-

(Python 2.x)

>>> 3/4

0

>>> 3.0/4

0.75

(Python 3.x)

>>> 3/4

0.75

>>> 'spam eggs'  # 작은 따옴표

'spam eggs'

>>> 'doesn\'t'  # 작은따옴표내에서 작은따옴표를 사용할 때 

"doesn't"

>>> "doesn't"  # 아니면 큰따옴표를 사용한다.

"doesn't"

>>> '"Yes," he said.'

'"Yes," he said.'

>>> "\"Yes,\" he said."

'"Yes," he said.'

>>> '"Isn\'t," she said.'

'"Isn\'t," she said.'

>>> print ('"Isn\'t," she said.')

"Isn't" she said.

>>> print('C:\some\name')  # here \n means newline!

C:\some

ame

>>> print(r'C:\some\name')  # note the r before the quote

C:\some\name

>>> print("""\

Usage: thingy [OPTIONS]

     -h                        Display this usage message

     -H hostname               Hostname to connect to

""")

Usage: thingy [OPTIONS]

     -h                        Display this usage message

     -H hostname               Hostname to connect to

>>> word = 'Python'

>>> word[0]  # character in position 0

'P'

>>> word[5]  # character in position 5

'n'

>>> word[-1]  # last character

'n'

>>> word[-2]  # second-last character

'o'

>>> word[-6]

'P'

>>> word[0:2]  # characters from position 0 (included) to 2 (excluded)

'Py'

>>> word[2:5]  # characters from position 2 (included) to 5 (excluded)

'tho'

>>> word[:2] + word[2:]

'Python'

>>> word[:4] + word[4:]

'Python'

>>> word[:2]  # character from the beginning to position 2 (excluded)

'Py'

>>> word[4:]  # characters from position 4 (included) to the end

'on'

>>> word[-2:] # characters from the second-last (included) to the end

'on'

>>> word[0] = 'J'

  ...

TypeError: 'str' object does not support item assignment

>>> word[2:] = 'py'

  ...

TypeError: 'str' object does not support item assignment

>>> squares = [1, 2, 4, 9, 16, 25]

>>> squares

[1, 2, 4, 9, 16, 25]

>>> squares[0]  # indexing returns the item

1

>>> squares[-1]

25

>>> squares[-3:]  # slicing returns a new list

[9, 16, 25]

>>> squares[:]

[1, 2, 4, 9, 16, 25]

>>> # Fibonacci series:

... # the sum of two elements defines the next

... a, b = 0, 1

>>> while b < 10:

...     print(b)

...     a, b = b, a+b

...

1

1

2

3

5

8