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2d Density Plots in Python

How to make a 2d density plot in python. Examples of density plots with kernel density estimations, custom color-scales, and smoothing.

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Version Check

Note: 2D Density Plots are available in version 2.0.0+
Run pip install plotly --upgrade to update your Plotly version

In [5]:
import plotly
plotly.__version__
Out[5]:
'2.0.2'

2D Histogram Contour Plot with Histogram Subplots

In [6]:
import plotly.plotly as py
import plotly.figure_factory as ff

import numpy as np

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))

colorscale = ['#7A4579', '#D56073', 'rgb(236,158,105)', (1, 1, 0.2), (0.98,0.98,0.98)]

fig = ff.create_2d_density(
    x, y, colorscale=colorscale,
    hist_color='rgb(255, 237, 222)', point_size=3
)

py.iplot(fig, filename='histogram_subplots')
Out[6]:

2D Histogram Contour Plot with Slider Control

Add slider controls to 2d-density-plot plots with the postMessage API.

See the code on JSFiddle.

Watch the 5 second video of how it works:

IPython terminal

Reference

In [7]:
help(ff.create_2d_density)
Help on function create_2d_density in module plotly.figure_factory._2d_density:

create_2d_density(x, y, colorscale='Earth', ncontours=20, hist_color=(0, 0, 0.5), point_color=(0, 0, 0.5), point_size=2, title='2D Density Plot', height=600, width=600)
    Returns figure for a 2D density plot
    
    :param (list|array) x: x-axis data for plot generation
    :param (list|array) y: y-axis data for plot generation
    :param (str|tuple|list) colorscale: 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) point_color: the color of the scatter points
    :param (str) point_size: the color of the scatter points
    :param (str) title: set the title for the plot
    :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.figure_factory create_2d_density
    
    import numpy as np
    
    # 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 = create_2D_density(x, y)
    
    # Plot the data
    py.iplot(fig, filename='simple-2d-density')
    ```
    
    Example 2: Using Parameters
    ```
    import plotly.plotly as py
    from plotly.figure_factory create_2d_density
    
    import numpy as np
    
    # 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 = create_2D_density(
        x, y, colorscale=colorscale,
        hist_color='rgb(255, 237, 222)', point_size=3)
    
    # Plot the data
    py.iplot(fig, filename='use-parameters')
    ```

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