DOC add links to github sourcecode in API reference

Makefile

@@ -28,7 +28,7 @@ test-code: in
 test-sphinxext:
 	$(NOSETESTS) -s -v doc/sphinxext/
 test-doc:
-	$(NOSETESTS) -s -v doc/ doc/modules/ doc/datasets/ \
+	$(NOSETESTS) -s -v doc/*.rst doc/modules/ doc/datasets/ \
 	doc/developers doc/tutorial/basic doc/tutorial/statistical_inference \
 	doc/tutorial/text_analytics
 

doc/conf.py

@@ -12,6 +12,7 @@
 # All configuration values have a default; values that are commented out
 # serve to show the default.
 
+from __future__ import print_function
 import sys
 import os
 from sklearn.externals.six import u
@@ -22,6 +23,8 @@
 # absolute, like shown here.
 sys.path.insert(0, os.path.abspath('sphinxext'))
 
+from github_link import make_linkcode_resolve
+
 # -- General configuration ---------------------------------------------------
 
 # Try to override the matplotlib configuration as early as possible
@@ -34,7 +37,8 @@
 # extensions coming with Sphinx (named 'sphinx.ext.*') or your custom ones.
 extensions = ['gen_rst',
               'sphinx.ext.autodoc', 'sphinx.ext.autosummary',
-              'sphinx.ext.pngmath', 'numpy_ext.numpydoc'
+              'sphinx.ext.pngmath', 'numpy_ext.numpydoc',
+              'sphinx.ext.linkcode',
               ]
 
 autosummary_generate = True
@@ -231,3 +235,10 @@ def setup(app):
     app.add_javascript('js/copybutton.js')
     # to format example galleries:
     app.add_javascript('js/examples.js')
+
+
+# The following is used by sphinx.ext.linkcode to provide links to github
+linkcode_resolve = make_linkcode_resolve('sklearn',
+                                         u'https://github.com/scikit-learn/'
+                                         'scikit-learn/blob/{revision}/'
+                                         '{package}/{path}#L{lineno}')

doc/sphinxext/github_link.py

@@ -0,0 +1,84 @@
+from operator import attrgetter
+import inspect
+import subprocess
+import os
+import sys
+from functools import partial
+
+REVISION_CMD = 'git rev-parse --short HEAD'
+
+
+def _get_git_revision():
+    try:
+        revision = subprocess.check_output(REVISION_CMD.split()).strip()
+    except subprocess.CalledProcessError:
+        print('Failed to execute git to get revision')
+        return None
+    return revision.decode('utf-8')
+
+
+def _linkcode_resolve(domain, info, package, url_fmt, revision):
+    """Determine a link to online source for a class/method/function
+
+    This is called by sphinx.ext.linkcode
+
+    An example with a long-untouched module that everyone has
+    >>> _linkcode_resolve('py', {'module': 'tty',
+    ...                          'fullname': 'setraw'},
+    ...                   package='tty',
+    ...                   url_fmt='http://hg.python.org/cpython/file/'
+    ...                           '{revision}/Lib/{package}/{path}#L{lineno}',
+    ...                   revision='xxxx')
+    'http://hg.python.org/cpython/file/xxxx/Lib/tty/tty.py#L18'
+    """
+
+    if revision is None:
+        return
+    if domain not in ('py', 'pyx'):
+        return
+    if not info.get('module') or not info.get('fullname'):
+        return
+
+    class_name = info['fullname'].split('.')[0]
+    if type(class_name) != str:
+        # Python 2 only
+        class_name = class_name.encode('utf-8')
+    module = __import__(info['module'], fromlist=[class_name])
+    obj = attrgetter(info['fullname'])(module)
+
+    try:
+        fn = inspect.getsourcefile(obj)
+    except Exception:
+        fn = None
+    if not fn:
+        try:
+            fn = inspect.getsourcefile(sys.modules[obj.__module__])
+        except Exception:
+            fn = None
+    if not fn:
+        return
+
+    fn = os.path.relpath(fn,
+                         start=os.path.dirname(__import__(package).__file__))
+    try:
+        lineno = inspect.getsourcelines(obj)[1]
+    except Exception:
+        lineno = ''
+    return url_fmt.format(revision=revision, package=package,
+                          path=fn, lineno=lineno)
+
+
+def make_linkcode_resolve(package, url_fmt):
+    """Returns a linkcode_resolve function for the given URL format
+
+    revision is a git commit reference (hash or name)
+
+    package is the name of the root module of the package
+
+    url_fmt is along the lines of ('https://github.com/USER/PROJECT/'
+                                   'blob/{revision}/{package}/'
+                                   '{path}#L{lineno}')
+    """
+    revision = _get_git_revision()
+    return partial(_linkcode_resolve, revision=revision, package=package,
+                   url_fmt=url_fmt)