I have a set of X,Y data points(from Remote sensing image),and I drew a scatter plot through the tutorial, the link is as follows:Generate a heatmap in MatPlotLib using a scatter data set
But when I try to draw a heat map, an error occurs：Heatmap cannot be displayed.
Is there a way to display two-dimensional data in a heat map, the different colors in the heat map represent the density of the pixels?
This is my code and result:
import rasterio
import numpy as np
import matplotlib.pyplot as plt
import matplotlib.cm as cm
from scipy.ndimage.filters import gaussian_filter
def myplot(x, y, s, bins=1000):
heatmap, xedges, yedges = np.histogram2d(x, y, bins=bins)
heatmap = gaussian_filter(heatmap, sigma=s)
extent = [xedges[0], xedges[-1], yedges[0], yedges[-1]]
return heatmap.T, extent
fig, axs = plt.subplots(1, 2)
dataset = rasterio.open('E:/Jupyter Notebook/LC81490312016259LGN00/LC8_subset_layerstacking.tif')
red_band = dataset.read(4)
NIR_band = dataset.read(5)
np.seterr(divide='ignore', invalid='ignore')
ndvi = (NIR_band.astype(float)-red_band.astype(float))/(NIR_band.astype(float)+red_band.astype(float))
ndvi_flat = np.ndarray.flatten(ndvi)
red_band_flat = np.ndarray.flatten(red_band)
x = ndvi_flat
y = red_band_flat
sigmas = [0, 16]
for ax, s in zip(axs.flatten(), sigmas):
if s == 0:
ax.plot(x, y, 'k.', markersize=0.1)
#ax.set_aspect('equal')
ax.set_title("Scatter plot")
ax.set_xlabel('NDVI')
ax.set_ylabel('Red Reflectance')
else:
img, extent = myplot(x, y, s)
ax.imshow(img, origin='lower',cmap=cm.jet)
ax.set_title("Smoothing with $\sigma$ = %d" % s)
ax.set_xlabel('NDVI')
ax.set_ylabel('Red Reflectance')
plt.show()
The left image is a black scatter plot (no pixel density information), and the right image is a heat map
The code and the data I need to process are stored in GitHub：https://github.com/Flyinfish-gzh/remote-sensing-data-visualization
