需要帮助写入 CSV 文件 Python 3.5

Question

我的代码写入一个名为“输出”的 CSV 文件， 这里是此代码过去帮助的链接当我运行我的代码时，我的 CSV 文件在正文行中被重写。 每次从stock table URL的表中抓取新信息时，我都想写入新行。 这是我的 CSV 文件的样子：

Index,P/E,EPS (ttm),Insider Own,Shs Outstand,Perf Week,Market Cap,Forward P/E,EPS next Y,Insider Trans,Shs Float,Perf Month,Income,PEG,EPS next Q,Inst Own,Short Float,Perf Quarter,Sales,P/S,EPS this Y,Inst Trans,Short Ratio,Perf Half Y,Book/sh,P/B,EPS next Y,ROA,Target Price,Perf Year,Cash/sh,P/C,EPS next 5Y,ROE,52W Range,Perf YTD,Dividend,P/FCF,EPS past 5Y,ROI,52W High,Beta,Dividend %,Quick Ratio,Sales past 5Y,Gross Margin,52W Low,ATR,Employees,Current Ratio,Sales Q/Q,Oper. Margin,RSI (14),Volatility,Optionable,Debt/Eq,EPS Q/Q,Profit Margin,Rel Volume,Prev Close,Shortable,LT Debt/Eq,Earnings,Payout,Avg Volume,Price,Recom,SMA20,SMA50,SMA200,Volume,Change

-,-,-3.00,45.18%,5.19M,30.47%,15.78M,-,-,0.00%,2.84M,-16.48%,-14.00M,-,-,1.00%,9.24%,88.82%,18.30M,0.86,-122.00%,136.99%,0.26,88.82%,27.27,0.11,-,-,4.00,-51.44%,0.87,3.51,15.00%,-,1.30 - 8.00,-27.10%,-,-,-15.40%,0.40%,-62.00%,2.73,-,1.10,-16.40%,25.10%,133.85%,0.52,450,1.20,-58.50%,-,53.21,19.81% 17.08%,No,0.37,-,-,5.40,2.96,Yes,0.13,-,-,991.40K,3.04,3.00,1.72%,-6.24%,29.44%,"5,358,503",2.70%

这是我的代码：

import csv
import urllib.request
from bs4 import BeautifulSoup

twiturl = "https://twitter.com/ACInvestorBlog"
twitpage = urllib.request.urlopen(twiturl)
soup = BeautifulSoup(twitpage,"html.parser")

print(soup.title.text)

tweets = [i.text for i in soup.select('a.twitter-cashtag.pretty-link.js-nav b')]
print(tweets)

url_base = "https://finviz.com/quote.ashx?t="
url_list = [url_base + tckr for tckr in tweets]

for url in url_list:

    fpage = urllib.request.urlopen(url)
    fsoup = BeautifulSoup(fpage, 'html.parser')

    #scrape single page and add data to list
    #write datalist
with open('output.csv', 'wt') as file:
    writer = csv.writer(file)

    # write header row
    writer.writerow(map(lambda e : e.text, fsoup.find_all('td', {'class':'snapshot-td2-cp'})))

    # write body row
    writer.writerow(map(lambda e : e.text, fsoup.find_all('td', {'class':'snapshot-td2'})))

Answer 1

追加模式

问题在于您的命令open('output.csv', 'wt') - 'w' 选项打开文件进行（覆盖）写入。 如果要在现有文件的末尾附加数据，请改用 'a' 选项，如https://docs.python.org/3.7/library/functions.html#open 上的精美手册所示。

此外，您可能希望事先检查文件是否存在，并仅在不存在时才写入标题行。