代码缩进引起的错误

问题描述:

老师你好，我按照视频写的代码没有输出，请问是什么原因？

同学的代码

from bs4 import BeautifulSoup

info = []
with open('/home/ee/Documents/1_2code_of_video/web/new_index.html', 'r') as wb_data:
    Soup = BeautifulSoup(wb_data, "lxml")
    images = Soup.select('body > div.main-content > ul > li > img')
    titles = Soup.select('body > div.main-content > ul > li > div.article-info > h3 > a')
    descs = Soup.select('body > div.main-content > ul > li > div.article-info > p.description')
    rates = Soup.select('body > div.main-content > ul > li > div.rate > span')
    cates = Soup.select('body > div.main-content > ul > li > div.article-info > p.meta-info')

for image,title,desc,rate,cate in zip(images,titles,descs,rates,cates):
    data = {
        'image': image.get('src'),
        'title': title.get_text(),
        'desc' : desc.get_text(),
        'rate' : rate.get_text(),
        'cate' : list(cate.stripped_strings)
            }

info.append(data)

for i in info:
    if float(i['rate'])>3:
        print(i['title'],i['cate'])

下面是运行结果：

/usr/bin/python3.5 /home/ee/Documents/1_2code_of_video/web/work2.py
Process finished with exit code 0

问题解答：

同学，你出现在缩进问题上，缩进不对，对代码逻辑就有影响了。 比如我先改改你的代码，先不判断分数是否大于3，我先看看info[ ]里面总共都有什么，如下：

from bs4 import BeautifulSoup

info = []
with open('/home/ee/Documents/1_2code_of_video/web/new_index.html', 'r') as wb_data:
    Soup = BeautifulSoup(wb_data, "lxml")
    images = Soup.select('body > div.main-content > ul > li > img')
    titles = Soup.select('body > div.main-content > ul > li > div.article-info > h3 > a')
    descs = Soup.select('body > div.main-content > ul > li > div.article-info > p.description')
    rates = Soup.select('body > div.main-content > ul > li > div.rate > span')
    cates = Soup.select('body > div.main-content > ul > li > div.article-info > p.meta-info')

for image,title,desc,rate,cate in zip(images,titles,descs,rates,cates):
    data = {
        'image': image.get('src'),
        'title': title.get_text(),
        'desc' : desc.get_text(),
        'rate' : rate.get_text(),
        'cate' : list(cate.stripped_strings)
            }

info.append(data)

for i in info:
    print (i['rate'])

------输出结果-------

3.0

那么现在就知道，其实info[ ]里面总共就一项数据，而且分数刚好等于3，所以按照你大于3分才输出的话，输出为空在逻辑上是正确的。

那么为什么不像视频那样输出结果呢？是因为你的info.append( data )这行代码没有放在for循环里面，也就是只是增加了数据的最后一项，正确的应该是这么写：

from bs4 import BeautifulSoup

info = []
with open('/home/ee/Documents/1_2code_of_video/web/new_index.html', 'r') as wb_data:
    Soup = BeautifulSoup(wb_data, "lxml")
    images = Soup.select('body > div.main-content > ul > li > img')
    titles = Soup.select('body > div.main-content > ul > li > div.article-info > h3 > a')
    descs = Soup.select('body > div.main-content > ul > li > div.article-info > p.description')
    rates = Soup.select('body > div.main-content > ul > li > div.rate > span')
    cates = Soup.select('body > div.main-content > ul > li > div.article-info > p.meta-info')

for image,title,desc,rate,cate in zip(images,titles,descs,rates,cates):
    data = {
        'image': image.get('src'),
        'title': title.get_text(),
        'desc' : desc.get_text(),
        'rate' : rate.get_text(),
        'cate' : list(cate.stripped_strings)
            }
    #问题在这里，缩进应该在for循环里面，不然没有添加每一项数据，永远都是最后一项
    info.append(data)

for i in info:
    if float(i['rate'])>3:
        print(i['title'],i['cate'])

--------输出结果------------

Sardinia's top 10 beaches ['fun', 'Wow']

How to get tanned ['butt', 'NSFW']

How to be an Aussie beach bum ['sea']