访问 python for 循环值

Question

我正在对 Python 进行一些试验，并尝试构建一个抓取工具。我已有的代码打印在下面。

import requests
from bs4 import BeautifulSoup
import csv

url = "http://www.grammy.com/nominees/search"
r = requests.get(url)

soup = BeautifulSoup(r.content)

g_data = soup.find_all("div", {"class": "view-content"})

f = csv.writer(open("file.csv", "w"))
f.writerow(["Year", "Category", "Title", "Winner"])

for item in g_data:
  for year in item.find_all("td", {"class": "views-field-year"}):
    year = year.contents[0]

  for category in item.find_all("td", {"class": "views-field-category-code"}):
    category = category.contents[0]

  for title in item.find_all("td", {"class": "views-field-field-nominee-work"}):
    title = title.contents[0]

  for winner in item.find_all("td", {"class": "views-field-field-nominee-extended"}):
    winner = winner.contents[0]

f.writerow([year, category, title, winner])

出于某种原因，CSV 文件只有 1 行，随机的。我如何才能访问其 for 范围之外的所有这些值？

Answer 1

你的写调用在你的循环之外，所以你只写了一行（最后一行）。缩进它，它应该按预期工作：

for item in g_data:
  for year in item.find_all("td", {"class": "views-field-year"}):
    year = year.contents[0]

  for category in item.find_all("td", {"class": "views-field-category-code"}):
    category = category.contents[0]

  for title in item.find_all("td", {"class": "views-field-field-nominee-work"}):
    title = title.contents[0]

  for winner in item.find_all("td", {"class": "views-field-field-nominee-extended"}):
    winner = winner.contents[0]

  f.writerow([year, category, title, winner])

如果您不熟悉 Python，代码块由缩进定义。

Answer 2

不仅是你最后的writerow()缩进不正确（应该在循环体下面）。此外，您需要遍历 tr 元素（代表包含数据的所需 table 中的每一行），为循环中找到的每个 tr 获取 td 元素。

我也会避免在循环中检查 td 元素的 class 属性值，而只是通过索引获取它们——换句话说，找到每个 td 元素的所有 tr 并得到 text.

修复和改进版本（仅 2 行代码）：

for item in soup.select("div.view-content table tr")[1:]:
    f.writerow([td.get_text(strip=True).encode("utf-8") for td in item.find_all("td")])

运行代码后file.csv的内容：

Year,Category,Title,Winner
2014,Record Of The Year,Stay With Me (Darkchild Version),"Sam Smith, artist. Steve Fitzmaurice, Rodney Jerkins & Jimmy Napes, producers. Matthew Champlin, Steve Fitzmaurice, Jimmy Napes & Steve Price, engineers/mixers. Tom Coyne, mastering engineer."
2014,Album Of The Year,Morning Phase,"Beck Hansen, producer; Tom Elmhirst, David Greenbaum, Cole Marsden Greif-Neill, Florian Lagatta, Robbie Nelson, Darrell Thorp, Cassidy Turbin & Joe Visciano, engineers/mixers; Bob Ludwig, mastering engineer."
2014,Song Of The Year,Stay With Me (Darkchild Version),"James Napier, William Phillips &Sam Smith, songwriters."
...
2014,Best Rap Song,I,"K. Duckworth, Ronald Isley & C. Smith, songwriters."
2014,Best Rap Album,The Marshall Mathers LP2,"Eminem, artist. Tony Campana, Joe Strange & Mike Strange, engineers/mixers."

访问 python for 循环值

Access python for loop values

python

csv

web-scraping

beautifulsoup

export-to-csv