Grabbing different elements with BeautifulSoup: avoid duplicating in nested elements

问题

i want to grab different content (classes) from an lokal saved website (the python documentation) using BeautifulSoup4, so i use this code for doing that (index.html is this saved website: https://docs.python.org/3/library/stdtypes.html )

from bs4 import BeautifulSoup
soup = BeautifulSoup(open("index.html"))
f = open('test.html','w')
f.truncate
classes= soup.find_all('dl', attrs={'class': ['class', 'method','function','describe', 'attribute', 'data', 'clasmethod', 'staticmethod']})
print(classes,file=f) 
f.close()

The filehandler is only for result-output and has no effect on the problem itself.

My problem is that the results are nested. For example the method "__eq__ (exporter) will be found 1. inside of the class and 2. as a method standalone.

So i want to remove all the results inside of other results to have every result on the same hierarchical level . How can i do this? Or is it even possible to "ignore" that content in the first step? I hope you understand what i mean.

回答1:

You cannot tell find to ignore nested dl elements; all you can do is ignore matches that appear in the .descendants:

matches = []
for dl in soup.find_all('dl', attrs={'class': ['class', 'method','function','describe', 'attribute', 'data', 'clasmethod', 'staticmethod']})
    if any(dl in m.descendants for m in matches):
        # child of already found element
        continue
    matches.append(dl)

If you want nested elements and no parents, use:

matches = []
for dl in soup.find_all('dl', attrs={'class': ['class', 'method','function','describe', 'attribute', 'data', 'clasmethod', 'staticmethod']})
    matches = [m for m in matches if dl not in m.descendants]
    matches.append(dl)

If you wanted to pull apart the tree and remove elements from the tree, use:

matches = soup.find_all('dl', attrs={'class': ['class', 'method','function','describe', 'attribute', 'data', 'clasmethod', 'staticmethod']})
for element in matches:
    element.extract()  # remove from tree (and parent `dl` matches)

but you may want to adjust your text extracting instead.

来源：https://stackoverflow.com/questions/23174251/grabbing-different-elements-with-beautifulsoup-avoid-duplicating-in-nested-elem

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python

beautifulsoup

html5lib