Python 代码在 csv 文件中仅打印一行

Question

最近我尝试编写一个 yp.com 列表刮板。 但无法弄清楚为什么代码在.csv 文件中只打印一行。

yp_urls.txt网址是：

https://www.yellowpages.com/search-map?search_terms=restaurant&geo_location_terms=波士顿https://www.yellowpages.com/search-map?search_terms=restaurant&page=2=Boston

这是代码：

from urllib.request import urlopen
from bs4 import BeautifulSoup as soup
with open('yp_urls.txt', 'r') as f:
    for url in f:
        print(url)        
        uClient = urlopen(url)
        page_html = uClient.read()        
        uClient.close()
        page_soup = soup(page_html, "html.parser")
        containers = page_soup.findAll("div",{"class":"v-card"})
        #container= containers[0]
        out_filename = "yp_listing.csv"
        headers = "URL \n"
        f = open(out_filename, "w")
f.write(headers)
for container in containers:
            business = container.a["href"].title()
print("business:" + business + "\n" )
f.write(business + "," + "\n")
f.close()  # Close the file

Answer 1

问题：

1. if 块的代码没有正确缩进。

2. 在 for 循环外打开 output 文件句柄。

尝试：

from urllib.request import urlopen
from bs4 import BeautifulSoup as soup

out_filename = "yp_listing.csv"
with open('yp_urls.txt', 'r') as f, open(out_filename, "w") as fout:
    headers = "URL \n"
    fout.write(headers)

    for url in f:
        print(url)        
        uClient = urlopen(url)
        page_html = uClient.read()        
        uClient.close()
        page_soup = soup(page_html, "html.parser")
        containers = page_soup.findAll("div",{"class":"v-card"})
        #container= containers[0]
        for container in containers:
            business = container.a["href"].title()
            print("business:" + business + "\n" )
            fout.write(business + "," + "\n")
#f.close()  # Close the file (closed by with)

Answer 2

f.write 命令似乎在您的循环之外，因此只有在循环完成后才会被命中。

例如，代码循环通过 url，然后退出循环并执行 f.write(headers)，然后循环通过容器，退出该循环和 f.write(business:..)

您可能还希望检查 output 文件是否在右侧 state 中以“w”（写入/覆盖）与“a”（附加）打开。 也许还可以考虑更改手柄，因此两者都不是“f”。