Clifford interact

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In [ ]:
import numpy as np
import pandas as pd
import datashader as ds
import panel as pn

from numba import jit
from datashader import transfer_functions as tf
from colorcet import palette_n


This example demonstrates how to use the pn.interact function to trigger updates in an image of a Clifford attractor generated using the Datashader library.

In [ ]:
def clifford_trajectory(a, b, c, d, x0, y0, n):
    xs, ys = np.zeros(n), np.zeros(n)
    xs[0], ys[0] = x0, y0
    for i in np.arange(n-1):
        xs[i+1] = np.sin(a * ys[i]) + c * np.cos(a * xs[i])
        ys[i+1] = np.sin(b * xs[i]) + d * np.cos(b * ys[i])
    return xs, ys

ps = {k:p[::-1] for k,p in palette_n.items()}

def clifford_plot(a=1.9, b=1.9, c=1.9, d=0.8, n=1000000, cmap=ps['kbc']):
    cvs = ds.Canvas(plot_width=600, plot_height=600)
    xs, ys = clifford_trajectory(a, b, c, d, 0, 0, n)
    df = pd.DataFrame(dict(x=xs,y=ys))
    agg = cvs.points(df, 'x', 'y')
    return tf.shade(agg, cmap=cmap)

pane = pn.interact(clifford_plot, a=(0,2), b=(0,2), c=(0,2), d=(0,2), n=(1,2e7), cmap=ps)
logo = ""
text = """<H4>Use the widgets to vary the parameters of this 
<a href="">Clifford attractor</a>.
<br><br>Note that many values result in nearly blank plots that contain only 
a few scattered points.</H4>"""

pn.Row(pn.Column(logo, text, pane[0]), pane[1]).servable()

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