切片，迭代,列表生成式的练习

Author: kangxiaoyu

2017-04-21/decorate.py

@@ -0,0 +1,15 @@
+#!/bin/env python
+
+
+# -*- coding:utf-8 -*-
+
+def log(func):
+	def wrapper(*args,**kw):
+		print('call %s():' % func.__name__)
+		return func(*args,**kw)
+	return wrapper
+@log
+def now():
+	print('2017-04-21')
+now()
+

2017-04-24/high_grade_feature/odd.py

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+#!/bin/env python
+# -*- coding:utf-8  -*-
+L=[]
+n=1
+while n <=99:
+	L.append(n)
+	n=n+2
+print L

2017-04-24/itera/for_2_variable.py

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+#!/bin/env python
+# -*- coding:utf-8 -*-
+from collections import Iterable
+for x,y in [(1,1),(2,4),(3,9)]:
+	print(x,y)

2017-04-24/itera/iterable2.py

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+#!/bin/env python
+# -*- coding:utf-8 -*-
+list=['kping','sguilian','xiaofei','xiaoxiao']
+for(i=0;i<list.length;i++){
+	n = list[i];
+	print n;
+}

2017-04-24/itera/iterable3.py

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+#!/bin/env python
+d={'a':1,'b':2,'c':3}
+for key in d:
+	print(key)

2017-04-24/itera/iteratale_str.py

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+#!/bin/env python
+# -*- coding:utf-8 -*-
+#这里可以写中文
+for ch in 'abc':
+	print(ch)

2017-04-24/itera/java_style_enumerate.py

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+#!/bin/env python
+# -*- coding:utf-8 -*-
+from collections import Iterable
+for i,value in enumerate(['A','B','C']):
+	print(i,value)
+

2017-04-24/itera/use_iterable.py

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+#!/bin/env python
+# -*- coding:utf-8 -*-
+from collections import Iterable
+print isinstance('abc',Iterable)
+print isinstance([1,2,3],Iterable)
+print isinstance(123,Iterable)
+

2017-04-24/list_generate/hello_list.py

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+#!/bin/env python
+# -*- coding:utf-8 -*-
+L=['Hello','world','ibm','apple']
+print [s.lower() for s in L]

2017-04-24/list_generate/list_g1.py

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

2017-04-24/list_generate/list_g2.py

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

2017-04-24/list_generate/list_g3.py

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

2017-04-24/list_generate/list_generate.py

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+#!/bin/env python
+# -*- coding:utf-8 -*-
+# 测试中文
+print list(range(1,11))
+L=[]
+for x in range(1,11):
+	L.append(x*x)
+print L
+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']

2017-04-24/list_generate/practice_list.py

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+#!/bin/env python
+# -*- coding:utf-8 -*-
+L = ['Hello', 'World', 18, 'Apple', None]
+print [s.lower() for s in L if isinstance(s, str) ]

2017-04-24/slice/last_slice.py

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+#!/bin/env python
+# -*- coding:utf-8 -*-
+L=['Michael','Sarah','Tracy','Bob','Jack']
+print L[-1]
+#print [-2:]
+print L[-2:-1]

2017-04-24/slice/no_slice1.py

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+#!/bin/env python
+# -*- coding:utf-8 -*-
+# 这里可以写中文呀.
+L=['Michael','Sarah','Tracy','Bob','Jack']
+
+print L[0],L[1],L[2]

2017-04-24/slice/no_slice2.py

@@ -0,0 +1,10 @@
+#!/bin/env python
+# -*- coding:utf-8 -*-
+# 这里可以写中文呀.
+L=['Michael','Sarah','Tracy','Bob','Jack']
+r=[]
+n=3
+for i in range(n):
+	r.append(L[i])
+print r
+#print L[0],L[1],L[2]

2017-04-24/slice/slice.py

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+#!/bin/env python
+# -*- coding:utf-8 -*-
+L=['Michael','Sarah','Tracy','Bob','Jack']
+print L[0:3]

2017-04-24/slice/slice11.py

@@ -0,0 +1,4 @@
+#!/bin/env python
+# -*- coding:utf-8 -*-
+L=['Michael','Sarah','Tracy','Bob','Jack']
+print L[:3]

2017-04-24/slice/slice22.py

@@ -0,0 +1,4 @@
+#!/bin/env python
+# -*- coding:utf-8 -*-
+L=['Michael','Sarah','Tracy','Bob','Jack']
+print L[1:3]

2017-04-24/slice/userful_slice.py

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+#!/bin/env python
+# -*- coding:utf-8 -*-
+L=list(range(100))
+print L
+print L[:10]
+print L[-10:]
+print L[10:20]
+print L[:10:2]
+print L[::5]
+#甚至什么都不写， 只写[:]就可以原样复制一个list
+print L[:]
+#tuple也是一种list,唯一区别式tuple不可变，因此，tuple也可以用切片操作，只是操作的结果仍是tuple
+print (0,1,2,3,4,5)[:3]
+

2017-04-24/slice/userful_slice2.py

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+#!/bin/env python
+# -*- coding:utf-8 -*-
+#字符串'xxx'也可以看成是一种list，每个元素就是一个字符。因此，字符串也可以用切片操作，只是操作结果仍是字符串：
+print 'ABCDEFG'[:3]
+print 'ABCDEFG'[::2]
+#在很多编程语言中，针对字符串提供了很多各种截取函数（例如，substring），其实目的就是对字符串切片。Python没有针对字符串的截取函数，只需要切片一个操作就可以完成，非常简单。
+
+#小结
+
+#有了切片操作，很多地方循环就不再需要了。Python的切片非常灵活，一行代码就可以实现很多行循环才能完成的操作。