python实现KNN算法中遇到的问题

1.缩进问题
IndentationError:uindent does not match any outer indentation level
错误原因：代码中添加了许多注释，打乱了缩进
解决办法：创建一个空白文件，不附带注释的重写代码，即好

2.属性错误
AttributeError:’dict’ object has no attribute ‘iteritems’
这个异常也是由于python3.x与python2.x的差别造成
2.1python3.x中dict methods dict.keys(), dict.items() and dict.values() return “views” instead of lists.
For example, this no longer works: k = d.keys(); k.sort(). Use k = sorted(d) instead (this works in Python 2.5 too and is just as efficient).
2.2the dict.iterkeys(), dict.iteritems() and dict.itervalues() methods are no longer supported.

3.print（）函数格式规范
python3.x相较于python2.x有很多变化：
python3.x使用 print( )function 代替 print satatement have been used in python2.x
eg：print x——>print(x)
print (x,y)——>print((x,y))
本以为是print( )格式规范出错，结果是python版本更新的兼容问题，下述博文中详细总结了print（）格式规范。   
http://blog.youkuaiyun.com/jcjc918/article/details/9354815
注：官方给出的python3中的改进部分“What’s New In Python 3.0”
https://docs.python.org/release/3.1.3/whatsnew/3.0.html

4.魔方变量_magic
以下网址中有详尽的解释。http://www.jianshu.com/p/1112320c5784