add samples

Author: michaelliao

samples/advance/do_generator.py

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+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+
+s = (x * x for x in range(5))
+print(s)
+for x in s:
+    print(x)
+
+def fib(max):
+    n, a, b = 0, 0, 1
+    while n < max:
+        yield b
+        a, b = b, a + b
+        n = n + 1
+    return 'done'
+
+f = fib(10)
+print('fib(10):', f)
+for x in f:
+    print(x)
+
+# call generator manually:
+g = fib(5)
+while 1:
+    try:
+        x = g.send(None)
+        print('g:', x)
+    except StopIteration as e:
+        print('Generator return value:', e.value)
+        break
+
+# call generator using iter:
+i = iter(fib(5))
+while 1:
+    try:
+        r = next(i)
+        print('i:', r)
+    except StopIteration as e:
+        print('Generator return value:', e.value)
+        break

samples/advance/do_iter.py

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+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+
+from collections import Iterable
+print('iterable? [1, 2, 3]:', isinstance([1, 2, 3], Iterable))
+print('iterable? \'abc\':', isinstance('abc', Iterable))
+print('iterable? 123:', isinstance(123, Iterable))
+
+# iter list:
+print('iter [1, 2, 3, 4, 5]')
+for x in [1, 2, 3, 4, 5]:
+    print(x)
+
+d = {'a': 1, 'b': 2, 'c': 3}
+
+# iter each key:
+print('iter key:', d)
+for k in d.keys():
+    print('key:', k)
+
+# iter each value:
+print('iter value:', d)
+for v in d.values():
+    print('value:', v)
+
+# iter both key and value:
+print('iter item:', d)
+for k, v in d.items():
+    print('item:', k, v)
+
+# iter list with index:
+print('iter enumerate([\'A\', \'B\', \'C\']')
+for i, value in enumerate(['A', 'B', 'C']):
+    print(i, value)
+
+# iter complex list:
+print('iter [(1, 1), (2, 4), (3, 9)]:')
+for x, y in [(1, 1), (2, 4), (3, 9)]:
+    print(x, y)

samples/advance/do_listcompr.py

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+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+
+print([x * x for x in range(1, 11)])
+print([x * x for x in range(1, 11) if x % 2 == 0])
+print([m + n for m in 'ABC' for n in 'XYZ'])
+
+d = {'x': 'A', 'y': 'B', 'z': 'C' }
+print([k + '=' + v for k, v in d.items()])
+
+L = ['Hello', 'World', 'IBM', 'Apple']
+print([s.lower() for s in L])

samples/advance/do_prod_cons.py

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+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+
+import time
+
+def consumer():
+    r = ''
+    while True:
+        n = yield r
+        if not n:
+            return
+        print('[CONSUMER] Consuming %s...' % n)
+        time.sleep(1)
+        r = '200 OK'
+
+def produce(c):
+    c.send(None)
+    n = 0
+    while n < 5:
+        n = n + 1
+        print('[PRODUCER] Producing %s...' % n)
+        r = c.send(n)
+        print('[PRODUCER] Consumer return: %s' % r)
+    c.close()
+
+c = consumer()
+produce(c)

samples/advance/do_slice.py

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+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+
+L = ['Michael', 'Sarah', 'Tracy', 'Bob', 'Jack']
+
+print('L[0:3] =', L[0:3])
+print('L[:3] =', L[:3])
+print('L[1:3] =', L[1:3])
+print('L[-2:] =', L[-2:])
+
+R = list(range(100))
+print('R[:10] =', R[:10])
+print('R[-10:] =', R[-10:])
+print('R[10:20] =', R[10:20])
+print('R[:10:2] =', R[:10:2])
+print('R[::5] =', R[::5])

samples/advance/do_yield.py

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+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+
+def each_ascii(s):
+    for ch in s:
+        yield ord(ch)
+    return '%s chars' % len(s)
+
+def yield_from(s):
+    r = yield from each_ascii(s)
+    print(r)
+
+def main():
+    for x in each_ascii('abc'):
+        print(x) # => 'a', 'b', 'c'
+    it = each_ascii('xyz')
+    try:
+        while True:
+            print(next(it)) # => 'x', 'y', 'z'
+    except StopIteration as s:
+        print(s.value) # => '3 chars'
+
+    # using yield from in main() will change main() from function to generator:
+    # r = yield from each_ascii('hello')
+
+    for ch in yield_from('hello'):
+        pass
+
+main()

samples/async/async_hello.py

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+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+
+import asyncio
+
+@asyncio.coroutine
+def hello():
+    print("Hello world!")
+    yield from asyncio.sleep(1)
+    print("Hello again!")
+
+loop = asyncio.get_event_loop()
+loop.run_until_complete(hello())
+loop.close()

samples/async/async_wget.py

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+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+
+import threading
+import asyncio
+
+@asyncio.coroutine
+def wget(host):
+    print('wget %s...' % host)
+    print('current thread: %s' % threading.current_thread())
+    connect = asyncio.open_connection(host, 80)
+    reader, writer = yield from connect
+    header = 'GET / HTTP/1.0\r\nHost: %s\r\n\r\n' % host
+    writer.write(header.encode('utf-8'))
+    yield from writer.drain()
+    while True:
+        line = yield from reader.readline()
+        if line == b'\r\n':
+            break
+        print('%s header > %s' % (host, line.decode('utf-8').rstrip()))
+    # Ignore the body, close the socket
+    writer.close()
+
+loop = asyncio.get_event_loop()
+tasks = [asyncio.async(wget(host)) for host in ['www.sina.com.cn', 'www.sohu.com', 'www.163.com']]
+for task in tasks:
+    loop.run_until_complete(task)
+loop.close()
+print('main thread: %s' % threading.current_thread())

samples/basic/do_for.py

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+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+
+# 打印list:
+names = ['Michael', 'Bob', 'Tracy']
+for name in names:
+    print(name)
+
+# 打印数字 0 - 9
+for x in range(10):
+    print(x)

samples/basic/do_if.py

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+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+
+# 注意:
+# input()返回的是字符串
+# 必须通过int()将字符串转换为整数
+# 才能用于数值比较:
+age = int(input('Input your age: '))
+
+if age >= 18:
+    print('adult')
+elif age >= 6:
+    print('teenager')
+else:
+    print('kid')

samples/basic/do_input.py

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+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+
+name = input()
+print('Hello,', name)

samples/basic/do_print.py

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+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+
+print('The quick brown fox', 'jumps over', 'the lazy dog')
+print(300)
+print(100 + 200)
+print('100 + 200 =', 100 + 200)

samples/basic/do_while.py

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+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+
+# 计算1+2+3+...+100:
+sum = 0
+n = 1
+while n <= 100:
+    sum = sum + n
+    n = n + 1
+print(sum)

samples/basic/hello.py

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+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+
+print('Hello, world')

samples/basic/the_dict.py

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+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+
+d = {
+    'Michael': 95,
+    'Bob': 75,
+    'Tracy': 85
+}
+print('d[\'Michael\'] =', d['Michael'])
+print('d[\'Bob\'] =', d['Bob'])
+print('d[\'Tracy\'] =', d['Tracy'])
+print('d.get(\'Thomas\', -1) =', d.get('Thomas', -1))

samples/basic/the_list.py

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+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+
+classmates = ['Michael', 'Bob', 'Tracy']
+print('classmates =', classmates)
+print('len(classmates) =', len(classmates))
+print('classmates[0] =', classmates[0])
+print('classmates[1] =', classmates[1])
+print('classmates[2] =', classmates[2])
+print('classmates[-1] =', classmates[-1])
+classmates.pop()
+print('classmates =', classmates)

samples/basic/the_set.py

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+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+
+s1 = set([1, 1, 2, 2, 3, 3])
+print(s1)
+s2 = set([2, 3, 4])
+print(s1 & s2)
+print(s1 | s2)

samples/basic/the_string.py

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+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+
+s = 'Python-中文'
+print(s)
+b = s.encode('utf-8')
+print(b)
+print(b.decode('utf-8'))

samples/basic/the_tuple.py

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+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+
+classmates = ('Michael', 'Bob', 'Tracy')
+print('classmates =', classmates)
+print('len(classmates) =', len(classmates))
+print('classmates[0] =', classmates[0])
+print('classmates[1] =', classmates[1])
+print('classmates[2] =', classmates[2])
+print('classmates[-1] =', classmates[-1])
+
+# cannot modify tuple:
+classmates[0] = 'Adam'

samples/commonlib/check_bmp.py

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+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+
+import struct
+
+bmp_header = b'\x42\x4d\x38\x8c\x0a\x00\x00\x00\x00\x00\x36\x00\x00\x00\x28\x00\x00\x00\x80\x02\x00\x00\x68\x01\x00\x00\x01\x00\x18\x00'
+
+print(struct.unpack('<ccIIIIIIHH', bmp_header))

samples/commonlib/do_base64.py

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+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+
+import base64
+
+s = base64.b64encode('在Python中使用BASE 64编码'.encode('utf-8'))
+print(s)
+d = base64.b64decode(s).decode('utf-8')
+print(d)
+
+s = base64.urlsafe_b64encode('在Python中使用BASE 64编码'.encode('utf-8'))
+print(s)
+d = base64.urlsafe_b64decode(s).decode('utf-8')
+print(d)

samples/commonlib/use_collections.py

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+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+
+from collections import namedtuple
+
+Point = namedtuple('Point', ['x', 'y'])
+p = Point(1, 2)
+print('Point:', p.x, p.y)
+
+from collections import deque
+
+q = deque(['a', 'b', 'c'])
+q.append('x')
+q.appendleft('y')
+print(q)
+
+from collections import defaultdict
+
+dd = defaultdict(lambda: 'N/A')
+dd['key1'] = 'abc'
+print('dd[\'key1\'] =', dd['key1'])
+print('dd[\'key2\'] =', dd['key2'])
+
+from collections import Counter
+c = Counter()
+for ch in 'programming':
+    c[ch] = c[ch] + 1
+print(c)