suggested details

Author: fchapoton

src/sage/plot/plot3d/parametric_plot3d.py

@@ -990,7 +990,7 @@ def g(x, y): return x, y+sin(y), x**2 + y**2
         f = tuple(f)
 
     if isinstance(f, (list, tuple)) and f and isinstance(f[0], (list, tuple)):
-        return sum([parametric_plot3d(v, urange, vrange, plot_points=plot_points, **kwds) for v in f])
+        return sum(parametric_plot3d(v, urange, vrange, plot_points=plot_points, **kwds) for v in f)
 
     if not isinstance(f, (tuple, list)) or len(f) != 3:
         raise ValueError("f must be a list, tuple, or vector of length 3")

src/sage/plot/plot3d/plot3d.py

@@ -190,8 +190,12 @@ def __init__(self, dep_var, indep_vars):
             Arbitrary Coordinates coordinate transform (z in terms of x, y)
         """
         all_vars = sage_getargspec(self.transform).args[1:]
-        if set(all_vars) != set(indep_vars + [dep_var]):
-            raise ValueError('variables were specified incorrectly for this coordinate system; incorrect variables were %s' % list(set(all_vars).symmetric_difference(set(indep_vars + [dep_var]))))
+        A = set(all_vars)
+        B = set(indep_vars + [dep_var])
+        if A != B:
+            raise ValueError('variables were specified incorrectly for this '
+                             'coordinate system; incorrect variables '
+                             'were %s' % list(A.symmetric_difference(B)))
         self.dep_var = dep_var
         self.indep_vars = indep_vars
 

src/sage/plot/plot3d/plot_field3d.py

@@ -150,10 +150,12 @@ def cm(x):
     scaled_vectors = [v / max_len for v in vectors]
 
     if center_arrows:
-        G = sum([plot(v, color=cm(v.norm()), **kwds).translate(p - v / 2) for v, p in zip(scaled_vectors, points)])
+        G = sum(plot(v, color=cm(v.norm()), **kwds).translate(p - v / 2)
+                for v, p in zip(scaled_vectors, points))
         G._set_extra_kwds(kwds)
         return G
     else:
-        G = sum([plot(v, color=cm(v.norm()), **kwds).translate(p) for v, p in zip(scaled_vectors, points)])
+        G = sum(plot(v, color=cm(v.norm()), **kwds).translate(p)
+                for v, p in zip(scaled_vectors, points))
         G._set_extra_kwds(kwds)
         return G