polar

This example shows how to use polar coordinates to generate a grid of polar plots of rose/rohdonea curves.

Details

Bokeh APIs:

bokeh.io.show, bokeh.models.ColumnDataSource, bokeh.models.PolarTransform, bokeh.plotting.figure, figure.line, bokeh.plotting.gridplot

More info:

Polar grid example

Keywords:

polar coordinates, rose curves, rohdonea curves

from fractions import Fraction
from math import pi

import numpy as np

from bokeh.colors.named import colors
from bokeh.io import show
from bokeh.models import ColumnDataSource, Plot, PolarTransform
from bokeh.plotting import figure, gridplot

dark_colors = iter(color for color in colors if color.brightness < 0.6)
color_map = {}

def rose(k: Fraction, A: float = 1) -> Plot:
    n = k.numerator
    d = k.denominator

    T = d*(2 if n*d % 2 == 0 else 1)

    angle = np.linspace(0, T*pi, T*100)
    radius = A*np.cos(float(k)*angle)

    source = ColumnDataSource(dict(radius=radius, angle=angle))
    t = PolarTransform()

    plot = figure(
        width=100, height=100,
        min_border=0,
        x_axis_type=None, y_axis_type=None,
        outline_line_color=None,
    )

    if k in color_map:
        color = color_map[k]
    else:
        color = color_map[k] = next(dark_colors)

    plot.line(x=t.x, y=t.y, line_color=color, source=source)

    return plot

def grid(N: int, D: int):
    for d in range(1, D + 1):
        for n in range(1, N + 1):
            yield rose(Fraction(n, d))

plot = gridplot(list(grid(9, 9)), ncols=9)
show(plot)