Python version and Device used
I'm following the BeautifulSoup tutorial but when I try to parse a xml page using the lxml library I get the following error:
bs4.FeatureNotFound: Couldn't find a tree builder with the features you requested:
lxml,xml. Do you need to install a parser library?
I am sure that I already installed lxml by all methods: easy_install, pip, port, etc. I tried to add a line to my code to see if lxml is installed or not:
import lxml
Then python can just successfully go through this code and display the previous error message again, occurring at the same line.
So I am quite sure that lxml was installed, but not installed correctly. So I decided to uninstall lxml, and then re-install using a 'correct' method. But when I type in
easy_install -m lxml
I get the following error:
Searching for lxml
Best match: lxml 3.2.1
Processing lxml-3.2.1-py2.7-macosx-10.6-intel.egg
Using /Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/lxml-
3.2.1-py2.7-macosx-10.6-intel.egg
Because this distribution was installed --multi-version, before you can
import modules from this package in an application, you will need to
'import pkg_resources' and then use a 'require()' call similar to one of
these examples, in order to select the desired version:
pkg_resources.require("lxml") # latest installed version
pkg_resources.require("lxml==3.2.1") # this exact version
pkg_resources.require("lxml>=3.2.1") # this version or higher
Processing dependencies for lxml
Finished processing dependencies for lxml
So I don't know how to continue my uninstall, I looked up many posts about this issue on google but still I can't find any useful info.
import mechanize
from bs4 import BeautifulSoup
import lxml
class count:
def __init__(self,protein):
self.proteinCode = protein
self.br = mechanize.Browser()
def first_search(self):
#Test 0
soup = BeautifulSoup(self.br.open("http://www.ncbi.nlm.nih.gov/protein/21225921?report=genbank&log$=prottop&blast_rank=1&RID=YGJHMSET015"), ['lxml','xml'])
return
if __name__=='__main__':
proteinCode = sys.argv[1]
gogogo = count(proteinCode)
I am using BeautifulSoup 4.3.2 and OS X 10.6.8. I also have a problem with improperly installed lxml
. Here are some things that I found out:
First of all, check this related question: Removed MacPorts, now Python is broken
Now, in order to check which builders for BeautifulSoup 4 are installed, try
>>> import bs4
>>> bs4.builder.builder_registry.builders
If you don't see your favorite builder, then it is not installed, and you will see an error as above ("Couldn't find a tree builder...").
Also, just because you can import lxml
, doesn't mean that everything is perfect.
Try
>>> import lxml
>>> import lxml.etree
To understand what's going on, go to the bs4
installation and open the egg (tar -xvzf
). Notice the modules bs4.builder
. Inside it you should see files such as _lxml.py
and _html5lib.py
. So you can also try
>>> import bs4.builder.htmlparser
>>> import bs4.builder._lxml
>>> import bs4.builder._html5lib
If there is a problem, you will see, why a parricular module cannot be loaded. You can notice how at the end of builder/__init__.py
it loads all those modules and ignores whatever was not loaded:
# Builders are registered in reverse order of priority, so that custom
# builder registrations will take precedence. In general, we want lxml
# to take precedence over html5lib, because it's faster. And we only
# want to use HTMLParser as a last result.
from . import _htmlparser
register_treebuilders_from(_htmlparser)
try:
from . import _html5lib
register_treebuilders_from(_html5lib)
except ImportError:
# They don't have html5lib installed.
pass
try:
from . import _lxml
register_treebuilders_from(_lxml)
except ImportError:
# They don't have lxml installed.
pass