TypeError：無法將字節連接到str

Question

我正在嘗試作為教程的一個例子。 此代碼的目的是讀取URL，為公司列表提取股票值並打印該值。 我有什么，試圖拼湊一些建議其他帖子，原始代碼（Python 3）是：

import urllib.request
import re

Symbols = ['aapl', 'spy' , 'goog' , 'nflx']
i = 0
while i < len(Symbols):
    Yahoo='http://finance.yahoo.com/q?s=' + Symbols[i]
    htmlfile = urllib.request.urlopen(Yahoo)
    htmltext = htmlfile.read()
    pattern= re.compile(b'<span id="yfs_l84_'+ Symbols[i] +'">(.+?)</span>')
    price= re.findall(pattern, htmltext)
    print('The price of' + (Symbols[i]) + ' is ' + str(price))
    i+=1

我知道html.read（）的輸出是以字節為單位的，所以我需要將我的正則表達式模式轉換為'bytes'（使用'b'），然后我得到的錯誤信息是：

Traceback (most recent call last):
  File "C:/Users/User/Documents/Raspberry Pi/Python/web scraper/web_scraper_v2.1.py", line 11, in
    price= re.findall(pattern, htmltext)
  File "C:\Python33\lib\re.py", line 201, in findall
    return _compile(pattern, flags).findall(string)
TypeError: can't use a string pattern on a bytes-like object

我懷疑這是語法相關的，但無法解決任何建議嗎？

Answer 1

干得好：

import urllib.request
import re

Symbols = ['aapl', 'spy', 'goog', 'nflx']
i = 0
while i < len(Symbols):
    Yahoo = 'http://finance.yahoo.com/q?s=' + Symbols[i]
    htmlfile = urllib.request.urlopen(Yahoo)
    htmltext = htmlfile.read()
    # Changed the string below so that we can resolve the problems with putting the
    # symbol value in the right place. str.format has been used instead
    # Also, the string has been made into a normal string again
    pattern = re.compile('<span id="yfs_l84_{symbol}">(.+?)</span>'.format(symbol=Symbols[i]))
    # Here htmltext is turned into a string so that we can compare, without the type-error
    price = re.findall(pattern, str(htmltext))
    print('The price of' + (Symbols[i]) + ' is ' + str(price))
    i += 1