added graphical tables + pep8 formatting

src/sage/matrix/operation_table.py

@@ -383,6 +383,7 @@ class OperationTable(SageObject):
 
     - Rob Beezer (2010-03-15)
     """
+
     def __init__(self, S, operation, names='letters', elements=None):
         r"""
         TESTS::
@@ -397,7 +398,7 @@ def __init__(self, S, operation, names='letters', elements=None):
         # Note: there exist listable infinite objects (like ZZ)
         if (elements is None):
             if hasattr(S, 'is_finite'):
-                if not(S.is_finite()):
+                if not (S.is_finite()):
                     raise ValueError('%s is infinite' % S)
             try:
                 try:
@@ -411,7 +412,7 @@ def __init__(self, S, operation, names='letters', elements=None):
             try:
                 for e in elements:
                     coerced = S(e)
-                    if not(coerced in elems):
+                    if not (coerced in elems):
                         elems.append(coerced)
             except Exception:
                 raise TypeError('unable to coerce %s into %s' % (e, S))
@@ -432,7 +433,7 @@ def __init__(self, S, operation, names='letters', elements=None):
         supported = {
             add: (add, '+', '+'),
             mul: (mul, '*', '\\ast')
-            }
+        }
         # default symbols for upper-left-hand-corner of table
         self._ascii_symbol = '.'
         self._latex_symbol = '\\cdot'
@@ -451,7 +452,7 @@ def __init__(self, S, operation, names='letters', elements=None):
         # the elements might not be hashable. But if they are it is much
         # faster to lookup in a hash table rather than in a list!
         try:
-            get_row = {e: i for i,e in enumerate(self._elts)}.__getitem__
+            get_row = {e: i for i, e in enumerate(self._elts)}.__getitem__
         except TypeError:
             get_row = self._elts.index
 
@@ -461,7 +462,8 @@ def __init__(self, S, operation, names='letters', elements=None):
                 try:
                     result = self._operation(g, h)
                 except Exception:
-                    raise TypeError('elements %s and %s of %s are incompatible with operation: %s' % (g,h,S,self._operation))
+                    raise TypeError('elements %s and %s of %s are incompatible with operation: %s' % (
+                        g, h, S, self._operation))
 
                 try:
                     r = get_row(result)
@@ -477,7 +479,8 @@ def __init__(self, S, operation, names='letters', elements=None):
                         except (KeyError, ValueError):
                             failed = True
                     if failed:
-                        raise ValueError('%s%s%s=%s, and so the set is not closed' % (g, self._ascii_symbol, h, result))
+                        raise ValueError('%s%s%s=%s, and so the set is not closed' % (
+                            g, self._ascii_symbol, h, result))
 
                 row.append(r)
             self._table.append(row)
@@ -558,7 +561,8 @@ def _name_maker(self, names):
             else:
                 width = int(log(self._n - 1, base)) + 1
             for i in range(self._n):
-                places = Integer(i).digits(base=base, digits=letters, padto=width)
+                places = Integer(i).digits(
+                    base=base, digits=letters, padto=width)
                 places.reverse()
                 name_list.append(''.join(places))
         elif names == 'elements':
@@ -570,19 +574,22 @@ def _name_maker(self, names):
                 name_list.append(estr)
         elif isinstance(names, list):
             if len(names) != self._n:
-                raise ValueError('list of element names must be the same size as the set, %s != %s'%(len(names), self._n))
+                raise ValueError('list of element names must be the same size as the set, %s != %s' % (
+                    len(names), self._n))
             width = 0
             for name in names:
                 if not isinstance(name, str):
-                    raise ValueError('list of element names must only contain strings, not %s' % name)
+                    raise ValueError(
+                        'list of element names must only contain strings, not %s' % name)
                 if len(name) > width:
                     width = len(name)
                 name_list.append(name)
         else:
-            raise ValueError("element names must be a list, or one of the keywords: 'letters', 'digits', 'elements'")
+            raise ValueError(
+                "element names must be a list, or one of the keywords: 'letters', 'digits', 'elements'")
         name_dict = {}
         for i in range(self._n):
-            name_dict[name_list[i]]=self._elts[i]
+            name_dict[name_list[i]] = self._elts[i]
         return width, name_list, name_dict
 
     def __getitem__(self, pair):
@@ -632,13 +639,15 @@ def __getitem__(self, pair):
             IndexError: invalid indices of operation table: ((1,512), (1,3,2,4)(5,7))
         """
         if not (isinstance(pair, tuple) and len(pair) == 2):
-            raise TypeError('indexing into an operation table requires exactly two elements')
+            raise TypeError(
+                'indexing into an operation table requires exactly two elements')
         g, h = pair
         try:
             row = self._elts.index(g)
             col = self._elts.index(h)
         except ValueError:
-            raise IndexError('invalid indices of operation table: (%s, %s)' % (g, h))
+            raise IndexError(
+                'invalid indices of operation table: (%s, %s)' % (g, h))
         return self._elts[self._table[row][col]]
 
     def __eq__(self, other):
@@ -747,8 +756,9 @@ def set_print_symbols(self, ascii, latex):
             ...
             ValueError: ASCII symbol should be a single character, not 5
         """
-        if not isinstance(ascii, str) or not len(ascii)==1:
-            raise ValueError('ASCII symbol should be a single character, not %s' % ascii)
+        if not isinstance(ascii, str) or not len(ascii) == 1:
+            raise ValueError(
+                'ASCII symbol should be a single character, not %s' % ascii)
         if not isinstance(latex, str):
             raise ValueError('LaTeX symbol must be a string, not %s' % latex)
         self._ascii_symbol = ascii
@@ -935,22 +945,53 @@ def matrix_of_variables(self):
         from sage.rings.rational_field import QQ
         R = PolynomialRing(QQ, 'x', self._n)
         MS = MatrixSpace(R, self._n, self._n)
-        entries = [R('x'+str(self._table[i][j])) for i in range(self._n) for j in range(self._n)]
-        return MS( entries )
-
-    #def color_table():
-        #r"""
-        #Returns a graphic image as a square grid where entries are color coded.
-        #"""
-        #pass
-        #return None
-
-    #def gray_table():
-        #r"""
-        #Returns a graphic image as a square grid where entries are coded as grayscale values.
-        #"""
-        #pass
-        #return None
+        entries = [R('x'+str(self._table[i][j]))
+                   for i in range(self._n) for j in range(self._n)]
+        return MS(entries)
+
+    def color_table(self, element_names=True, cmap=gist_rainbow, **options):
+        r"""
+        Returns a graphic image as a square grid where entries are color coded.
+
+        INPUT:
+
+        - ``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
+
+        - ``**options`` - passed on to matrix_plot call
+
+        """
+
+        # Base matrix plot object, without text
+        plot = matrix_plot(Matrix(self._table), cmap=cmap,
+                           frame=False, **options)
+
+        if element_names:
+
+            # adapted from ._ascii_table()
+            # prepare widenames[] list for labelling on image
+            n = self._n
+            width = self._width
+
+            widenames = []
+            for name in self._names:
+                widenames.append("{0: >{1}s}".format(name, width))
+
+            # iterate through each element
+            for g in range(n):
+                for h in range(n):
+
+                    # add text to the plot
+                    tPos = (g, h)
+                    tText = widenames[self._table[g][h]]
+                    t = text(tText, tPos, rgbcolor=(0, 0, 0))
+                    plot = plot + t
+
+        return plot
+
+    def gray_table(self, **options):
+        return self.color_table(cmap=Greys, **options)
 
     def _ascii_table(self):
         r"""
@@ -1031,7 +1072,7 @@ def _ascii_table(self):
             widenames.append('{0: >{1}s}'.format(name, width))
 
         # Headers
-        table = ['{0: >{1}s} '.format(self._ascii_symbol,width)]
+        table = ['{0: >{1}s} '.format(self._ascii_symbol, width)]
         table += [' '+widenames[i] for i in range(n)]+['\n']
         table += [' ']*width + ['+'] + ['-']*(n*(width+1))+['\n']
 
@@ -1068,7 +1109,8 @@ def _latex_(self):
 
         # Row label and body of table
         for g in range(n):
-            table.append('{}')  # Interrupts newline and [], so not line spacing
+            # Interrupts newline and [], so not line spacing
+            table.append('{}')
             table.append(names[g])
             for h in range(n):
                 table.append('&'+names[self._table[g][h]])