NameError：未定义全局名称“ operator” [英] NameError: global name 'operator' is not defined

问题描述

import KNN
def c(i,d,l,k):
    dss=d.shape[0]
    dm=tile(i,(dss,1))-d
    sqm=dm**2
    sqd=sqm.sum(axis=1)
    dist=sqd**0.5
    sDI=dist.argsort()
    clc={}
    for i in range(k):
        vl=l[sDI[i]]
        clc[vl]=clc.get(vl,0)+1     
    sCC=sorted(clc.items(),key=operator.itemgetter(1),reverse=True)
    return sCC[0][0]

c([0,0],g,l,3)

错误：

Traceback (most recent call last):
  File "<pyshell#32>", line 1, in <module>
    c([0,0],g,l,3)
  File "<pyshell#31>", line 12, in c
    sCC=sorted(clc.items(),key=operator.itemgetter(1),reverse=True)
NameError: global name 'operator' is not defined

KNN包含以下代码：

KNN contains the following code:

from numpy import *
import operator

def createDataSet():
    group = array([[1.0,1.1],[1.0,1.0],[0,0],[0,0.1]])
    labels = ['A','A','B','B']
    return group, labels

为什么会出现上述错误？程序在Python 3.3.2上运行。这段代码是在Python中运行的简单的k分类算法。

Why is there a error as mentioned above? Program is run on Python 3.3.2. This code is a simple k-classification algorithm run in Python.

推荐答案

您需要 import运算符到本地名称空间； import KNN 也不会导入它导入的子模块。

You need to import operator into the local namespace; import KNN will not also import the submodules it imports.

通常，您需要明确说明任何以及您使用的所有模块和对象，但 builtins （ https://docs.python.org/2/library/functions.html ）。

As a rule, you need to be explicit about any and all modules and objects you use, with the exception of the builtins (https://docs.python.org/2/library/functions.html).

与某些其他语言不同，没有隐式导入。

Unlike some other languages, there are no implicit imports.

有关导入的高级技巧/教程：
您可能会想使用 KNN.operator 。它在这里可用，因为它是由 KNN 导入的。但是，这几乎总是令人遗憾的决定，因为这使情况感到困惑：这是一个特殊的模块吗？如果是这样，它的界面是什么？保存可爱性，要明确。

Advanced tip/editorial on imports: You might be tempted to use KNN.operator. It's available there because it was imported by KNN. However, this is almost always a regrettable decision, as confuses the picture: Is this a special module? If so what's its interface? Save the cuteness, be explicit.

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