Added _make_colorscale method and 2D Density Plot

Author: Kully

plotly/tools.py

@@ -1476,6 +1476,149 @@ class FigureFactory(object):
     more information and examples of a specific chart type.
     """
 
+    @staticmethod
+    def _make_colorscale(colors):
+        """
+        Makes a list of colors into a colorscale-acceptable form
+
+        For documentation regarding to the form of the output, see
+        https://plot.ly/python/reference/#mesh3d-colorscale
+        """
+        colorscale = []
+        diff = 1./(len(colors) - 1)
+
+        for j in range(len(colors)):
+            colorscale.append([j * diff, colors[j]])
+        return colorscale
+
+    @staticmethod
+    def create_2D_density(x, y, colorscale='Earth', ncontours=20,
+                          hist_color=(0, 0, 0.5), pt_color=(0, 0, 0.5),
+                          pt_size=2, height=600, width=600):
+        """
+        Returns figure for a 2D density plot
+
+        :param (list) x: x-axis data for plot generation
+        :param (list) y: y-axis data for plot generation
+        :param (str|tuple|list) colormap: either a plotly scale name, an rgb
+            or hex color, a color tuple or a list or tuple of colors. An rgb
+            color is of the form 'rgb(x, y, z)' where x, y, z belong to the
+            interval [0, 255] and a color tuple is a tuple of the form
+            (a, b, c) where a, b and c belong to [0, 1]. If colormap is a
+            list, it must contain the valid color types aforementioned as its
+            members.
+        :param (int) ncontours: the number of 2D contours to draw on the plot
+        :param (str) hist_color: the color of the plotted histograms
+        :param (str) pt_color: the color of the scatter points
+        :param (str) pt_size: the color of the scatter points
+        :param (float) height: the height of the chart
+        :param (float) width: the width of the chart
+
+        Example 1: Simple 2D Density Plot
+        ```
+        import plotly.plotly as py
+        from plotly.tools import FigureFactory as FF
+
+        # Make data points
+        t = np.linspace(-1,1.2,2000)
+        x = (t**3)+(0.3*np.random.randn(2000))
+        y = (t**6)+(0.3*np.random.randn(2000))
+
+        # Create a figure
+        fig = FF.create_2D_density(x, y)
+
+        # Plot the data
+        py.iplot(fig, filename='simple-2d-density')
+        ```
+
+        Example 2: Use Parameters
+        ```
+        import plotly.plotly as py
+        from plotly.tools import FigureFactory as FF
+
+        # Make data points
+        t = np.linspace(-1,1.2,2000)
+        x = (t**3)+(0.3*np.random.randn(2000))
+        y = (t**6)+(0.3*np.random.randn(2000))
+
+        # Create custom colorscale
+        colorscale = ['#7A4579', '#D56073', 'rgb(236,158,105)',
+                      (1, 1, 0.2), (0.98,0.98,0.98)]
+
+        # Create a figure
+        fig = FF.create_2D_density(
+            x, y, colorscale=colorscale, hist_color='rgb(255, 237, 222)', pt_size=3)
+
+        # Plot the data
+        py.iplot(fig, filename='use-parameters')
+        ```
+        """
+        from plotly.graph_objs import graph_objs
+        colorscale = FigureFactory._validate_colors(colorscale, 'rgb')
+        colorscale = FigureFactory._make_colorscale(colorscale)
+
+        # validate hist_color and pt_color
+        hist_color = FigureFactory._validate_colors(hist_color, 'rgb')
+        pt_color = FigureFactory._validate_colors(pt_color, 'rgb')
+
+        trace1 = graph_objs.Scatter(
+            x=x, y=y, mode='markers', name='points',
+            marker=dict(
+                color=pt_color[0],
+                size=pt_size,
+                opacity=0.4
+            )
+        )
+        trace2 = graph_objs.Histogram2dcontour(
+            x=x, y=y, name='density', ncontours=ncontours,
+            colorscale=colorscale, reversescale=True, showscale=False
+        )
+        trace3 = graph_objs.Histogram(
+            x=x, name='x density',
+            marker=dict(color=hist_color[0]), yaxis='y2'
+        )
+        trace4 = graph_objs.Histogram(
+            y=y, name='y density',
+            marker=dict(color=hist_color[0]), xaxis='x2'
+        )
+        data = [trace1, trace2, trace3, trace4]
+
+        layout = graph_objs.Layout(
+            showlegend=False,
+            autosize=False,
+            title='Love',
+            height=height,
+            width=width,
+            xaxis=dict(
+                ___domain=[0, 0.85],
+                showgrid=False,
+                zeroline=False
+            ),
+            yaxis=dict(
+                ___domain=[0, 0.85],
+                showgrid=False,
+                zeroline=False
+            ),
+            margin=dict(
+                t=50
+            ),
+            hovermode='closest',
+            bargap=0,
+            xaxis2=dict(
+                ___domain=[0.85, 1],
+                showgrid=False,
+                zeroline=False
+            ),
+            yaxis2=dict(
+                ___domain=[0.85, 1],
+                showgrid=False,
+                zeroline=False
+            )
+        )
+
+        fig = graph_objs.Figure(data=data, layout=layout)
+        return fig
+
     @staticmethod
     def _validate_gantt(df):
         """