import datashader as ds
import datashader.transfer_functions as tf
from datashader import spatial

from colorcet import fire

%%time
df = spatial.read_parquet('./data/osm-1billion.parq')
df = df.persist()

print(len(df))
df.head()

bound = 20026376.39
bounds = dict(x_range = (-bound, bound), y_range = (int(-bound*0.4), int(bound*0.6)))
plot_width = 900
plot_height = int(plot_width*0.5)

%%time
cvs = ds.Canvas(plot_width=plot_width, plot_height=plot_height, **bounds)
agg2=cvs.points(df, 'x', 'y', ds.count())

%%time
cvs = ds.Canvas(plot_width=plot_width, plot_height=plot_height, **bounds)
agg = cvs.points(df, 'x', 'y', ds.count())

tf.shade(agg, cmap=["lightblue", "darkblue"], how='log')

tf.shade(agg.where(agg > 15), cmap=["lightblue", "darkblue"])

tf.set_background(tf.shade(agg.where(agg > 15), cmap=fire),"black")

import holoviews as hv
from holoviews import opts
from holoviews.operation.datashader import datashade, dynspread
hv.extension('bokeh')

rgb_opts = opts.RGB(width=plot_width,height=plot_height, xaxis=None, yaxis=None, bgcolor="black")
points = hv.Points(df, ['x', 'y']).redim.range(x=bounds["x_range"],y=bounds["y_range"])
rgb = dynspread(datashade(points, cmap=["darkblue", "lightcyan"], width=plot_width,height=plot_height))
rgb.opts(rgb_opts)