@@ -174,12 +174,17 @@ if plotly_available:

     def convert_cmap_list_mpl_plotly(mpl_cmap_name, N=255):

-        cmap_mpl = matplotlib.cm.get_cmap(mpl_cmap_name)

-        cmap_mpl_arr = matplotlib.colors.makeMappingArray(N, cmap_mpl)

-        level = np.linspace(0, 1, N)

-        cmap_plotly_linear = [(level, convert_colormap_mpl_plotly(cmap_mpl))

-                                for level, cmap_mpl in zip(level,

-                                                            cmap_mpl_arr)]

+        if isinstance(mpl_cmap_name, str):

+            cmap_mpl = matplotlib.cm.get_cmap(mpl_cmap_name)

+            cmap_mpl_arr = matplotlib.colors.makeMappingArray(N, cmap_mpl)

+            level = np.linspace(0, 1, N)

+            cmap_plotly_linear = [(level, convert_colormap_mpl_plotly(cmap_mpl))

+                                    for level, cmap_mpl in zip(level,

+                                                                cmap_mpl_arr)]

+        else:

+            assert(isinstance(mpl_cmap_name, list))

+            # Do not do any conversion if it's already a list

+            cmap_plotly_linear = mpl_cmap_name

         return cmap_plotly_linear

@@ -1612,6 +1612,7 @@ def mask_interpolate(coords, values, a=None, method='nearest', oversampling=3):

                  range(len(cmin)))

     grid = tuple(np.ogrid[dims])

     img = interpolate.griddata(coords, values, grid, method)

+    img = img.astype(np.float_)

     mask = np.mgrid[dims].reshape(len(cmin), -1).T

     # The numerical values in the following line are optimized for the common

     # case of a square lattice:

@@ -1793,7 +1794,8 @@ def _map_plotly(syst, img, colorbar, _max, _min,  vmin, vmax, overflow_pct,

     contour_object.y = np.linspace(_min[1],_max[1],img.shape[1])

     contour_object.zsmooth = False

     contour_object.connectgaps = False

-    contour_object.colorscale = _p.convert_cmap_list_mpl_plotly(cmap)

+    cmap = _p.convert_cmap_list_mpl_plotly(cmap)

+    contour_object.colorscale = cmap

     contour_object.zmax = vmax

     contour_object.zmin = vmin

     contour_object.hoverinfo = 'none'

@@ -116,18 +116,31 @@ def syst_3d(W=3, r1=2, r2=4, a=1, t=1.0):

     return syst

+def plotter_file_suffix(engine):

+    # We need this function so that we can add a .html suffix to the output filename.

+    # This is required because plotly will throw an error if filename is without the suffix.

+    if engine == "plotly":

+        return ".html"

+    else:

+        return None

+

+

 @pytest.mark.skipif(not _plotter.mpl_available, reason="Matplotlib unavailable.")

-def test_plot():

+def test_matplotlib_plot():

+

+    plotter.set_engine('matplotlib')

     plot = plotter.plot

     syst2d = syst_2d()

     syst3d = syst_3d()

     color_opts = ['k', (lambda site: site.tag[0]),

                   lambda site: (abs(site.tag[0] / 100),

                                 abs(site.tag[1] / 100), 0)]

-    with tempfile.TemporaryFile('w+b') as out:

+    engine = plotter.get_engine()

+    with tempfile.NamedTemporaryFile('w+b', suffix=plotter_file_suffix(engine)) as out:

+        out_filename = out.name

         for color in color_opts:

             for syst in (syst2d, syst3d):

-                fig = plot(syst, site_color=color, cmap='binary', file=out)

+                fig = plot(syst, site_color=color, cmap='binary', file=out_filename)

                 if (color != 'k' and

                     isinstance(color(next(iter(syst2d.sites()))), float)):

                     assert fig.axes[0].collections[0].get_array() is not None

@@ -137,30 +150,66 @@ def test_plot():

                                            abs(site.tag[1] / 100), 0)]

         for color in color_opts:

             for syst in (syst2d, syst3d):

-                fig = plot(syst2d, hop_color=color, cmap='binary', file=out,

+                fig = plot(syst2d, hop_color=color, cmap='binary', file=out_filename,

                            fig_size=(2, 10), dpi=30)

                 if color != 'k' and isinstance(color(next(iter(syst2d.sites())),

                                                           None), float):

                     assert fig.axes[0].collections[1].get_array() is not None

-        assert isinstance(plot(syst3d, file=out).axes[0], mplot3d.axes3d.Axes3D)

+        assert isinstance(plot(syst3d, file=out_filename).axes[0], mplot3d.axes3d.Axes3D)

+

+        syst2d.leads = []

+        plot(syst2d, file=out_filename)

+        del syst2d[list(syst2d.hoppings())]

+        plot(syst2d, file=out_filename)

+

+        plot(syst3d, file=out_filename)

+        with warnings.catch_warnings():

+            warnings.simplefilter("ignore")

+            plot(syst2d.finalized(), file=out_filename)

+

+        # test 2D projections of 3D systems

+        plot(syst3d, file=out_filename, pos_transform=lambda pos: pos[:2])

+

+

+@pytest.mark.skipif(not _plotter.plotly_available, reason="Plotly unavailable.")

+def test_plotly_plot():

+

+    plotter.set_engine('plotly')

+    plot = plotter.plot

+    syst2d = syst_2d()

+    syst3d = syst_3d()

+    color_opts = ['black', (lambda site: site.tag[0]),

+                  lambda site: (abs(site.tag[0] / 100),

+                                abs(site.tag[1] / 100), 0)]

+    engine = plotter.get_engine()

+    with tempfile.NamedTemporaryFile('w+b', suffix=plotter_file_suffix(engine)) as out:

+        out_filename = out.name

+        for color in color_opts:

+            for syst in (syst2d, syst3d):

+                plot(syst, site_color=color, cmap='binary', file=out_filename, show=False)

+

+        color_opts = ['black', (lambda site, site2: site.tag[0]),

+                      lambda site, site2: (abs(site.tag[0] / 100),

+                                           abs(site.tag[1] / 100), 0)]

         syst2d.leads = []

-        plot(syst2d, file=out)

+        plot(syst2d, file=out_filename, show=False)

         del syst2d[list(syst2d.hoppings())]

-        plot(syst2d, file=out)

+        plot(syst2d, file=out_filename, show=False)

-        plot(syst3d, file=out)

+        plot(syst3d, file=out_filename, show=False)

         with warnings.catch_warnings():

             warnings.simplefilter("ignore")

-            plot(syst2d.finalized(), file=out)

+            plot(syst2d.finalized(), file=out_filename, show=False)

         # test 2D projections of 3D systems

-        plot(syst3d, file=out, pos_transform=lambda pos: pos[:2])

+        plot(syst3d, file=out_filename, pos_transform=lambda pos: pos[:2], show=False)

 @pytest.mark.skipif(not _plotter.mpl_available, reason="Matplotlib unavailable.")

-def test_plot_more_site_families_than_colors():

+@pytest.mark.parametrize("engine", ["plotly", "matplotlib"])

+def test_plot_more_site_families_than_colors(engine):

     # test against regression reported in

     # https://gitlab.kwant-project.org/kwant/kwant/issues/257

     ncolors = len(pyplot.rcParams['axes.prop_cycle'])

@@ -169,17 +218,23 @@ def test_plot_more_site_families_than_colors():

                 for i in range(ncolors + 1)]

     for i, lat in enumerate(lattices):

         syst[lat(i, 0)] = None

-    with tempfile.TemporaryFile('w+b') as out:

-        plotter.plot(syst, file=out)

+

+    plotter.set_engine(engine)

+    with tempfile.NamedTemporaryFile('w+b', suffix=plotter_file_suffix(engine)) as out:

+        out_filename = out.name

+        print(out)

+        plotter.plot(syst, file=out_filename, show=False)

 @pytest.mark.skipif(not _plotter.mpl_available, reason="Matplotlib unavailable.")

-def test_plot_raises_on_bad_site_spec():

+@pytest.mark.parametrize("engine", ["plotly", "matplotlib"])

+def test_plot_raises_on_bad_site_spec(engine):

     syst = kwant.Builder()

     lat = kwant.lattice.square(norbs=1)

     syst[(lat(i, j) for i in range(5) for j in range(5))] = None

     # Cannot provide site_size as an array when syst is a Builder

+    plotter.set_engine(engine)

     with pytest.raises(TypeError):

         plotter.plot(syst, site_size=[1] * 25)

@@ -197,20 +252,24 @@ def bad_transform(pos):

     return x, y, 0

 @pytest.mark.skipif(not _plotter.mpl_available, reason="Matplotlib unavailable.")

-def test_map():

+@pytest.mark.parametrize("engine", ["plotly", "matplotlib"])

+def test_map(engine):

+    plotter.set_engine(engine)

     syst = syst_2d()

-    with tempfile.TemporaryFile('w+b') as out:

+

+    with tempfile.NamedTemporaryFile('w+b', suffix=plotter_file_suffix(engine)) as out:

+        out_filename = out.name

         plotter.map(syst, lambda site: site.tag[0], pos_transform=good_transform,

-                    file=out, method='linear', a=4, oversampling=4, cmap='flag')

+                    file=out_filename, method='linear', a=4, oversampling=4, cmap='flag', show=False)

         pytest.raises(ValueError, plotter.map, syst,

                       lambda site: site.tag[0],

-                      pos_transform=bad_transform, file=out)

+                      pos_transform=bad_transform, file=out_filename)

         with warnings.catch_warnings():

             warnings.simplefilter("ignore")

             plotter.map(syst.finalized(), range(len(syst.sites())),

-                        file=out)

+                        file=out_filename, show=False)

         pytest.raises(ValueError, plotter.map, syst,

-                      range(len(syst.sites())), file=out)

+                      range(len(syst.sites())), file=out_filename)

 def test_mask_interpolate():

@@ -233,22 +292,32 @@ def test_mask_interpolate():

 @pytest.mark.skipif(not _plotter.mpl_available, reason="Matplotlib unavailable.")

-def test_bands():

+@pytest.mark.parametrize("engine", ["plotly", "matplotlib"])

+def test_bands(engine):

+

+    plotter.set_engine(engine)

     syst = syst_2d().finalized().leads[0]

-    with tempfile.TemporaryFile('w+b') as out:

-        plotter.bands(syst, file=out)

-        plotter.bands(syst, fig_size=(10, 10), file=out)

-        plotter.bands(syst, momenta=np.linspace(0, 2 * np.pi), file=out)

+    with tempfile.NamedTemporaryFile('w+b', suffix=plotter_file_suffix(engine)) as out:

+        out_filename = out.name

+        plotter.bands(syst, show=False, file=out_filename)

+        plotter.bands(syst, show=False, momenta=np.linspace(0, 2 * np.pi), file=out_filename)

+

+        if engine == 'matplotlib':

+            plotter.bands(syst, show=False, fig_size=(10, 10), file=out_filename)

+

+            fig = pyplot.Figure()

+            ax = fig.add_subplot(1, 1, 1)

+            plotter.bands(syst, show=False, ax=ax, file=out_filename)

-        fig = pyplot.Figure()

-        ax = fig.add_subplot(1, 1, 1)

-        plotter.bands(syst, ax=ax, file=out)

 @pytest.mark.skipif(not _plotter.mpl_available, reason="Matplotlib unavailable.")

-def test_spectrum():

+@pytest.mark.parametrize("engine", ["plotly", "matplotlib"])

+def test_spectrum(engine):

+

+    plotter.set_engine(engine)

     def ham_1d(a, b, c):

         return a**2 + b**2 + c**2

@@ -264,38 +333,43 @@ def test_spectrum():

     vals = np.linspace(0, 1, 3)

-    with tempfile.TemporaryFile('w+b') as out:

+    with tempfile.NamedTemporaryFile('w+b', suffix=plotter_file_suffix(engine)) as out:

+        out_filename = out.name

         for ham in (ham_1d, ham_2d, fsyst):

-            plotter.spectrum(ham, ('a', vals), params=dict(b=1, c=1), file=out)

-            # test with explicit figsize

-            plotter.spectrum(ham, ('a', vals), params=dict(b=1, c=1),

-                             fig_size=(10, 10), file=out)

+            plotter.spectrum(ham, ('a', vals), params=dict(b=1, c=1), file=out_filename, show=False)

+            if engine == 'matplotlib':

+                # test with explicit figsize

+                plotter.spectrum(ham, ('a', vals), params=dict(b=1, c=1),

+                                 fig_size=(10, 10), file=out_filename, show=False)

         for ham in (ham_1d, ham_2d, fsyst):

             plotter.spectrum(ham, ('a', vals), ('b', 2 * vals),

-                             params=dict(c=1), file=out)

-            # test with explicit figsize

-            plotter.spectrum(ham, ('a', vals), ('b', 2 * vals),

-                             params=dict(c=1), fig_size=(10, 10), file=out)

-

-        # test 2D plot and explicitly passing axis

-        fig = pyplot.figure()

-        ax = fig.add_subplot(1, 1, 1, projection='3d')

-        plotter.spectrum(ham_1d, ('a', vals), ('b', 2 * vals),

-                         params=dict(c=1), ax=ax, file=out)

-        # explicitly pass axis without 3D support

-        ax = fig.add_subplot(1, 1, 1)

-        with pytest.raises(TypeError):

+                             params=dict(c=1), file=out_filename, show=False)

+            if engine == 'matplotlib':

+                # test with explicit figsize

+                plotter.spectrum(ham, ('a', vals), ('b', 2 * vals),

+                                 params=dict(c=1), fig_size=(10, 10), file=out_filename, show=False)

+

+        if engine == 'matplotlib':

+            # test 2D plot and explicitly passing axis

+            fig = pyplot.figure()

+            ax = fig.add_subplot(1, 1, 1, projection='3d')

             plotter.spectrum(ham_1d, ('a', vals), ('b', 2 * vals),

-                             params=dict(c=1), ax=ax, file=out)

+                             params=dict(c=1), ax=ax, file=out_filename, show=False)

+            # explicitly pass axis without 3D support

+            ax = fig.add_subplot(1, 1, 1)

+            with pytest.raises(TypeError):

+                plotter.spectrum(ham_1d, ('a', vals), ('b', 2 * vals),

+                                 params=dict(c=1), ax=ax, file=out_filename, show=False)

     def mask(a, b):

         return a > 0.5

-    with tempfile.TemporaryFile('w+b') as out:

+    with tempfile.NamedTemporaryFile('w+b', suffix=plotter_file_suffix(engine)) as out:

+        out_filename = out.name

         plotter.spectrum(ham, ('a', vals), ('b', 2 * vals), params=dict(c=1),

-                         mask=mask, file=out)

+                         mask=mask, file=out_filename, show=False)

 def syst_rect(lat, salt, W=3, L=50):

@@ -555,7 +629,7 @@ def test_current():

     current = J(kwant.wave_function(syst, energy=1)(1)[0])

     # Test good codepath

-    with tempfile.TemporaryFile('w+b') as out:

+    with tempfile.NamedTemporaryFile('w+b') as out:

         plotter.current(syst, current, file=out)

         fig = pyplot.Figure()