Unorderable Type错误在Python中意味着什么？

Question

from urllib.request import urlopen
page1 = urlopen("http://www.beans-r-us.biz/prices.html")
page2 = urlopen("http://www.beans-r-us.biz/prices-loyalty.html")
text1 = page1.read().decode("utf8")
text2 = page2.read().decode("utf8")
where = text2.find(">$")
start_of_price = where + 2
end_of_price = where + 6
price_loyal = text2[start_of_price:end_of_price]
price = text1[234:238]
password = 5501
p = input("Loyalty Customers Password? : ")
passkey = int(p)

if passkey == password:
    while price_loyal > 4.74:
        if price_loyal < 4.74:
            print("Here is the loyal customers price :) :")
            print(price_loyal)
        else:
            print( "Price is too high to make a profit, come back later :) ")
else:
    print("Sorry incorrect password :(, here is the normal price :")
    print(price)
input("Thanks for using our humble service, come again :), press enter to close this window.")

我遇到的问题是它一直运行直到我得到4.74部分.然后它停止并抱怨一种不可理解的类型.我对这意味着什么感到困惑.

Answer 1

price_loyal是一个字符串(即使它包含你找到的数字find),你试图与数值(4.75)进行比较？为了比较试试

float(price_loyal)

更新(谢谢@agf):

使用Python v 3.x,您会收到您提到的错误消息.

>>> price_loyal = '555.5'
>>> price_loyal  > 5000.0
Traceback (most recent call last):
  File "<pyshell#1>", line 1, in <module>
    price_loyal > 5000.0
TypeError: unorderable types: str() > float()
>>> 

而

>>> float(price_loyal) > 5000.0
False

Python的版本在这种情况下有所不同,所以总是可以提到一个正在使用的版本.以前......使用Python v 2.x

您的比较将在不转换string为float第一个的情况下关闭.例如,

price_loyal
'555.5'

这与string和float的比较给出了 True

price_loyal > 5000.0
True

这与float和float的比较给出False了应有的效果

float(price_loyal) > 5000.0
False

可能还有其他问题,但这看起来像是一个问题.