使用类函数将多个参数传递给pool.map [英] Passing multiple arguments to pool.map using class function

问题描述

我正在尝试按照这篇文章中所述进行线程化，并通过工作在Python 2.7中传递多个参数-此处中所述.

I'm trying to thread as described in this post, and also pass multiple arguments in Python 2.7 through a work-around described here.

现在我有类似这样的功能，它是类pair_scraper的一部分:

Right now I have something like this, a function that is part of class pair_scraper:

def pool_threading(self):
        pool = ThreadPool(4)
        for username in self.username_list:
            master_list = pool.map(self.length_scraper2,
                itertools.izip(username*len(self.repo_list),
                itertools.repeat(self.repo_list)))

def length_scraper2(self, username, repo):
    #code

但是，当我运行代码时，出现错误消息:

However, when I run my code I get the error:

TypeError: length_scraper2() takes exactly 3 arguments (2 given)

这似乎是因为它希望将self作为参数传递，考虑到我在类中使用类函数，这是没有意义的.关于如何解决的想法?

Which seems to be because it wants self passed as an argument, which is nonsensical given I'm using a class function within the class. Thoughts on how to fix?

推荐答案

itertools.izip(username*len(self.repo_list),itertools.repeat(self.repo_list))产生tuple.

您需要显式地将2个参数传递给您的方法(self被隐式传递，因为它是一个非静态方法)，但是您仅显式地传递1个元组，加上隐式的self可以传递2个参数，因此令人困惑的错误消息.

You need to pass 2 arguments explicitly to your method (self is implicitly passed because it's a non-static method), but you only pass 1 tuple explicitly, plus the implicit self which makes 2 arguments, hence the confusing error message.

您必须使用*将元组作为2个单独的参数传递，如下所示:

You have to use * to pass your tuple as 2 separate arguments, like this:

master_list = pool.map(self.length_scraper2,
     *itertools.izip(username*len(self.repo_list),itertools.repeat(self.repo_list)))

使用经典map在简单函数上进行的简单测试:

simple test using the classical map on a simple function:

def function(b,c):
    return (b,c)

print(list(map(function,zip([1,2],[4,5]))))

错误:

  print(list(map(function,zip([1,2],[4,5]))))
 TypeError: function() missing 1 required positional argument: 'c'

现在添加单个星号以扩展args:

now adding single asterisk to expand args:

print(list(map(function,*zip([1,2],[4,5]))))

有效:

[(1, 2), (4, 5)]

类方法相同:

class Foo:
    def function(self,b,c):
        return (b,c)

f = Foo()

print(list(map(f.function,*zip([1,2],[4,5]))))

这篇关于使用类函数将多个参数传递给pool.map的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！