Extract raster values from vector file

Easily extract raster values from vector files (polygon/point)

Import librairies

import museotoolbox as mtb
import numpy as np

Load HistoricalMap dataset

raster,vector = mtb.datasets.load_historical_data()

Extract raster values with no vector information

X = mtb.processing.extract_ROI(raster,vector)

print("Vector contains {} pixels".format(X.shape[0]))
print("Raster contains {} bands per pixel".format(X.shape[1]))

Out:

Vector contains 12657 pixels
Raster contains 3 bands per pixel

Let’s suppose you want konw to extract the label of each polygon/point

X,y = mtb.processing.extract_ROI(raster,vector,'class')
uniqueLabels = np.unique(y,return_counts=True)

for label,count in zip(*uniqueLabels):
    print('label {} has {} samples'.format(label,count))

Out:

label 1 has 7544 samples
label 2 has 2296 samples
label 3 has 2283 samples
label 4 has 525 samples
label 5 has 9 samples

You can put as many fields as you want, except fields of string type

X,y,g = mtb.processing.extract_ROI(raster,vector,'class','uniquefid')
print('There are a total of {} groups'.format(np.unique(g).size))

Out:

There are a total of 17 groups