import json
import zipfile
import numpy as np
import pandas as pd
import matplotlib.pyplot as plt

zf = zipfile.ZipFile('sample.zip')
df = pd.read_csv(zf.open('sample.csv'), converters={'POLYLINE': lambda x: json.loads(x)[-1:]})
latlong = np.array([[p[0][1], p[0][0]] for p in df['POLYLINE'] if len(p)>0])
lat_low, lat_hgh = np.percentile(latlong[:,0], [2, 98])
lon_low, lon_hgh = np.percentile(latlong[:,1], [2, 98])
bins = 513
lat_bins = np.linspace(lat_low, lat_hgh, bins)
lon_bins = np.linspace(lon_low, lon_hgh, bins)
H2, _, _ = np.histogram2d(latlong[:,0], latlong[:,1], bins=(lat_bins, lon_bins))

img = np.log(H2[::-1, :] + 1)
plt.figure()
ax = plt.subplot(1,1,1)
plt.imshow(img)
plt.axis('off')