MAINT moved axhline into it's own module

This is part of the refactoring process. All plots methods should be moved to their own modules. In this commit, I've started the refactoring by moving the axhline to its own module, lines, which should contain lines and spans plotting function.
matplotlib · NelleV · Jul 11, 2013 · Jul 11, 2013 · Jul 11, 2013 · Jul 11, 2013
commit a7291a86e90f15e212f15c7ccb279314c44c2d52
diff --git a/lib/matplotlib/axes/_axes.py b/lib/matplotlib/axes/_axes.py
@@ -34,6 +34,8 @@
 from matplotlib.container import BarContainer, ErrorbarContainer, StemContainer
 from matplotlib.axes._base import _AxesBase
 
+from . import _lines
+
 iterable = cbook.iterable
 is_string_like = cbook.is_string_like
 is_sequence_of_strings = cbook.is_sequence_of_strings
@@ -591,77 +593,9 @@ def annotate(self, *args, **kwargs):
 
     #### Lines and spans
 
-    @docstring.dedent_interpd
     def axhline(self, y=0, xmin=0, xmax=1, **kwargs):
-        """
-        Add a horizontal line across the axis.
-
-        Parameters
-        ----------
-        y : scalar, optional, default: 0
-            y position in data coordinates of the horizontal line.
-
-        xmin : scalar, optional, default: 0
-            Should be between 0 and 1, 0 being the far left of the plot, 1 the
-            far right of the plot.
-
-        xmax : scalar, optional, default: 1
-            Should be between 0 and 1, 0 being the far left of the plot, 1 the
-            far right of the plot.
-
-        Returns
-        -------
-        `~matplotlib.lines.Line2D`
-
-        Notes
-        -----
-        kwargs are the same as kwargs to plot, and can be
-        used to control the line properties.  e.g.,
-
-        Examples
-        --------
-
-        * draw a thick red hline at 'y' = 0 that spans the xrange::
-
-            >>> axhline(linewidth=4, color='r')
-
-        * draw a default hline at 'y' = 1 that spans the xrange::
-
-            >>> axhline(y=1)
-
-        * draw a default hline at 'y' = .5 that spans the the middle half of
-          the xrange::
-
-            >>> axhline(y=.5, xmin=0.25, xmax=0.75)
-
-        Valid kwargs are :class:`~matplotlib.lines.Line2D` properties,
-        with the exception of 'transform':
-
-        %(Line2D)s
-
-        See also
-        --------
-        `axhspan` for example plot and source code
-        """
-
-        if "transform" in kwargs:
-            raise ValueError(
-                "'transform' is not allowed as a kwarg;"
-                + "axhline generates its own transform.")
-        ymin, ymax = self.get_ybound()
-
-        # We need to strip away the units for comparison with
-        # non-unitized bounds
-        self._process_unit_info(ydata=y, kwargs=kwargs)
-        yy = self.convert_yunits(y)
-        scaley = (yy < ymin) or (yy > ymax)
-
-        trans = mtransforms.blended_transform_factory(
-            self.transAxes, self.transData)
-        l = mlines.Line2D([xmin, xmax], [y, y], transform=trans, **kwargs)
-        self.add_line(l)
-        self.autoscale_view(scalex=False, scaley=scaley)
-        return l
+        return _lines.axhline(self, y=0, xmin=0, xmax=1, **kwargs)
+    axhline.__doc__ = _lines.axhline.__doc__
 
     @docstring.dedent_interpd
     def axvline(self, x=0, ymin=0, ymax=1, **kwargs):

diff --git a/lib/matplotlib/axes/_lines.py b/lib/matplotlib/axes/_lines.py
@@ -0,0 +1,80 @@
+"""
+Lines and spans
+"""
+
+from matplotlib import docstring
+from matplotlib import transforms as mtransforms
+from matplotlib import line as mlines
+
+
+@docstring.dedent_interpd
+def axhline(ax, y=0, xmin=0, xmax=1, **kwargs):
+    """
+    Add a horizontal line across the axis.
+
+    Parameters
+    ----------
+    y : scalar, optional, default: 0
+        y position in data coordinates of the horizontal line.
+
+    xmin : scalar, optional, default: 0
+        Should be between 0 and 1, 0 being the far left of the plot, 1 the
+        far right of the plot.
+
+    xmax : scalar, optional, default: 1
+        Should be between 0 and 1, 0 being the far left of the plot, 1 the
+        far right of the plot.
+
+    Returns
+    -------
+    `~matplotlib.lines.Line2D`
+
+    Notes
+    -----
+    kwargs are the same as kwargs to plot, and can be
+    used to control the line properties.  e.g.,
+
+    Examples
+    --------
+
+    * draw a thick red hline at 'y' = 0 that spans the xrange::
+
+        >>> axhline(linewidth=4, color='r')
+
+    * draw a default hline at 'y' = 1 that spans the xrange::
+
+        >>> axhline(y=1)
+
+    * draw a default hline at 'y' = .5 that spans the the middle half of
+        the xrange::
+
+        >>> axhline(y=.5, xmin=0.25, xmax=0.75)
+
+    Valid kwargs are :class:`~matplotlib.lines.Line2D` properties,
+    with the exception of 'transform':
+
+    %(Line2D)s
+
+    See also
+    --------
+    `axhspan` for example plot and source code
+    """
+
+    if "transform" in kwargs:
+        raise ValueError(
+            "'transform' is not allowed as a kwarg;"
+            + "axhline generates its own transform.")
+    ymin, ymax = ax.get_ybound()
+
+    # We need to strip away the units for comparison with
+    # non-unitized bounds
+    ax._process_unit_info(ydata=y, kwargs=kwargs)
+    yy = ax.convert_yunits(y)
+    scaley = (yy < ymin) or (yy > ymax)
+
+    trans = mtransforms.blended_transform_factory(
+        ax.transAxes, ax.transData)
+    l = mlines.Line2D([xmin, xmax], [y, y], transform=trans, **kwargs)
+    ax.add_line(l)
+    ax.autoscale_view(scalex=False, scaley=scaley)
+    return l