Failed to install Scikit-learn in Ubuntu 16.04

I am trying to install Scikit-learn in Ubuntu 16.04, but there is an error when I am trying to install. I had successfully installed following packages

• Python 2.7.12
• NumPy 1.11.0
• SciPy 0.17.0

But the output of the command pip install -U scikit-learn is

Collecting scikit-learn
Exception:
Traceback (most recent call last): File "/usr/lib/python2.7/dist-packages/pip/basecommand.py", line 209, in main status = self.run(options, args) File "/usr/lib/python2.7/dist-packages/pip/commands/install.py", line 328, in run wb.build(autobuilding=True) File "/usr/lib/python2.7/dist-packages/pip/wheel.py", line 748, in build self.requirement_set.prepare_files(self.finder) File "/usr/lib/python2.7/dist-packages/pip/req/req_set.py", line 360, in prepare_files ignore_dependencies=self.ignore_dependencies)) File "/usr/lib/python2.7/dist-packages/pip/req/req_set.py", line 512, in _prepare_file finder, self.upgrade, require_hashes) File "/usr/lib/python2.7/dist-packages/pip/req/req_install.py", line 273, in populate_link self.link = finder.find_requirement(self, upgrade) File "/usr/lib/python2.7/dist-packages/pip/index.py", line 442, in find_requirement all_candidates = self.find_all_candidates(req.name) File "/usr/lib/python2.7/dist-packages/pip/index.py", line 400, in find_all_candidates for page in self._get_pages(url_locations, project_name): File "/usr/lib/python2.7/dist-packages/pip/index.py", line 545, in _get_pages page = self._get_page(location) File "/usr/lib/python2.7/dist-packages/pip/index.py", line 648, in _get_page return HTMLPage.get_page(link, session=self.session) File "/usr/lib/python2.7/dist-packages/pip/index.py", line 757, in get_page "Cache-Control": "max-age=600", File "/usr/share/python-wheels/", line 480, in get return self.request('GET', url, **kwargs) File "/usr/lib/python2.7/dist-packages/pip/download.py", line 378, in request return super(PipSession, self).request(method, url, *args, **kwargs) File "/usr/share/python-wheels/", line 468, in request resp = self.send(prep, **send_kwargs) File "/usr/share/python-wheels/", line 576, in send r = adapter.send(request, **kwargs) File "/usr/share/python-wheels/", line 46, in send resp = super(CacheControlAdapter, self).send(request, **kw) File "/usr/share/python-wheels/", line 376, in send timeout=timeout File "/usr/share/python-wheels/", line 610, in urlopen _stacktrace=sys.exc_info()[2]) File "/usr/share/python-wheels/", line 228, in increment total -= 1
TypeError: unsupported operand type(s) for -=: 'Retry' and 'int'

What can I do to solve this problem? Thank you in advance.

2 Answers

This error may be because you are behind a proxy. Try to connect to a network without proxy (e.g. your home), unset proxy environment variables:unset http_proxy, unset http_proxy, unset HTTP_PROXY, unset HTTPS_PROXYThen run your command again.pip install -U scikit-learn

I think you should change pip to pip2.7, because, in Ubuntu 16.04, the pip function is considered to be pip3 (for python3):

pip2.7 install -U scikit-learn