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Parameter arrow for geom_spoke()

Note that the lengths of the arrow heads depend on the total lengths of the arrows.

In [1]:
import numpy as np

from lets_plot import *
In [2]:
LetsPlot.setup_html()
In [3]:
def F(xarray, yarray):
    return yarray, -xarray

def cartesian_to_polar(xarray, yarray):
    rarray = np.sqrt(xarray**2 + yarray**2)
    return rarray / rarray.max(), np.arctan2(yarray, xarray)
In [4]:
n = 11
a, b = -5, 5
space = np.linspace(a, b, n)
X, Y = np.meshgrid(space, space)
R, A = cartesian_to_polar(*F(X, Y))
data = dict(x=X.reshape(-1), y=Y.reshape(-1), r=R.reshape(-1), a=A.reshape(-1))
In [5]:
ggplot(data, aes('x', 'y', color='r')) + \
    geom_spoke(aes(angle='a', radius='r'), \
               arrow=arrow(type='closed', angle=12, length=15)) + \
    scale_color_gradient(low='#3288bd', high='#d53e4f', guide='none') + \
    coord_fixed(xlim=[a, b], ylim=[a, b]) + \
    theme_minimal() + \
    theme(axis_text=element_text(margin=10), axis_title='blank')
Out[5]: