Question

我正在创建一个函数来分析硒页面

def get_position_links(start_url, browser):
    """
    Retrieve the position_links 
    """
    position_links = []
    next_page_element = ""
    next_page_attribute = ""

    #kick off
    browser.get(start_url)

    def get_position_links_and_next_page_elememnt_in_the_current_page(position_links):
        ##Get the position_links within the page
        #browser change appropriately with the page change
        nonlocal  next_page_element
        nonlocal  next_page_attribute
        position_elements = browser.find_elements_by_class_name("position_link")  # Retrieve the postions link elements
        #select those only contain python in the title
        position_elements = [p for p in position_elements if "python" in p.text.lower()]
        #position_links as global variable set at the top
        position_links.extend([p.get_attribute("href") for p in position_elements])

        #nonlocal to avoied repeated return
        next_page_element = browser.find_element_by_class_name("pager_next")
        #next_page_attribute for the while flag.
        next_page_attribute = next_page_element.get_attribute("class").strip()

    #handle the start_url
    get_position_links_and_next_page_elememnt_in_the_current_page()

    #Traverse until there's no next pages.
    while not next_page_attribute.endswith("disabled"):
        # time.sleep(random.uniform(1,20))
        next_page_element.click()
        get_position_links_and_next_page_elememnt_in_the_current_page()

    return position_links

在封闭的函数中，我声明了next_page_element = "" next_page_attribute = ""，但不确定它们的数据类型。

但是，我应该为它们随机设置一种数据类型，
如何设置没有默认数据类型（如

）的变量

var nextPageElement
var nextPageAttribute

使用Javascript？

Answer 1

您可以使用此函数查找变量的数据类型。

type（）

例如

a = 1.0
print(type(a))

Output: <class 'float'>

显式数据类型转换称为“类型转换”

显式数据类型转换的一般形式是

> (required_data_type)(expression)

您可以深入研究一些常用的显式数据类型转换。

链接：https://www.datacamp.com/community/tutorials/python-data-type-conversion

Answer 2

我根本看不出有任何理由使用非局部变量。您应该只从函数中返回值。

def get_position_links_and_next_page_elememnt_in_the_current_page(position_links):
    ...
    return next_page_element, next_page_attribute 

next_page_element, next_page_attribute = get_position_links_and_next_page_elememnt_in_the_current_page(position_links)

现在，您不需要非本地的，您不需要预定义元素，甚至根本不需要嵌套的函数。

设置变量时不使用默认数据类型

2 个答案: