improve imports + doc tweaks

Author: Bruno-TT

src/sage/matrix/operation_table.py

@@ -17,7 +17,6 @@
 from sage.structure.sage_object import SageObject
 from matplotlib.cm import gist_rainbow, Greys
 from sage.plot.matrix_plot import matrix_plot
-from sage.matrix.constructor import Matrix
 from sage.plot.text import text
 from sage.all import copy
 
@@ -950,11 +949,17 @@ def matrix_of_variables(self):
                    for i in range(self._n) for j in range(self._n)]
         return MS(entries)
 
+
+    ### documentation hack ###
+    # this code makes the docs display the default
+    # argument of color_table as "gist_rainbow"
+    # instead of something like 
+    # <matplotlib.colors.LinearSegmentedColormap object at 0x7fc24f7e10a0>
     gist_rainbow_copy=copy(gist_rainbow)
-    class ReprOverrideLinearSegmentedColormap(gist_rainbow_copy.__class__):
+    class _ReprOverrideLinearSegmentedColormap(gist_rainbow_copy.__class__):
         def __repr__(self):
-            return "Matplotlib gist_rainbow colormap"
-    gist_rainbow_copy.__class__=ReprOverrideLinearSegmentedColormap
+            return "gist_rainbow"
+    gist_rainbow_copy.__class__=_ReprOverrideLinearSegmentedColormap
 
 
     def color_table(self, element_names=True, cmap=gist_rainbow_copy, **options):
@@ -965,11 +970,12 @@ def color_table(self, element_names=True, cmap=gist_rainbow_copy, **options):
 
         - ``element_names`` - (default : ``True``) Whether to display text with element names on the image
 
-        - ``cmap`` - (default : ``gist_rainbow``) colour map for plot, see matplotlib.cm
+        - ``cmap`` - (default : ``gist_rainbow``) matplotlib colour map object for plot
 
         - ``**options`` - passed on to matrix_plot call
 
         EXAMPLES::
+
             sage: from sage.matrix.operation_table import OperationTable
             sage: OT = OperationTable(SymmetricGroup(3), operation=operator.mul)
             sage: OT.color_table()
@@ -978,7 +984,7 @@ def color_table(self, element_names=True, cmap=gist_rainbow_copy, **options):
         """
 
         # Base matrix plot object, without text
-        plot = matrix_plot(Matrix(self._table), cmap=cmap,
+        plot = matrix_plot(self._table, cmap=cmap,
                            frame=False, **options)
 
         if element_names:
@@ -1009,6 +1015,13 @@ def color_table(self, element_names=True, cmap=gist_rainbow_copy, **options):
         return plot
 
     def gray_table(self, **options):
+        r"""
+        See ``color_table`` - this uses a grey colour scheme instead of a colourful one.
+
+        INPUT:
+
+        - ``**options`` - passed on to ``color_table`` call
+        """
         return self.color_table(cmap=Greys, **options)
 
     def _ascii_table(self):