"""Implementation of the NDXI family of features."""
from functools import partial
import numpy as np
from ..image import Image
from .feature import Feature
NDXI_TYPES = {
'nir_ndvi': ('nir-1', 'red'),
'rg_ndvi': ('red', 'green'),
'rb_ndvi': ('red', 'blue'),
'ndsi': ('nir-1', 'green'),
'ndwi': ('coastal', 'nir-2'),
'wvsi': ('green', 'yellow'),
}
def ndxi_image(image: Image, ndxi_type):
"""Calculates the feature according to the ndxi option provided."""
band_0_name, band_1_name = NDXI_TYPES[ndxi_type]
band_0 = image[band_0_name]
band_1 = image[band_1_name]
band_mix = band_0 + band_1
# Ignore divide, this division may complain about division by 0
# This usually happens in the edge, which is alright by us.
old_settings = np.seterr(divide='ignore', invalid='ignore')
ndxi = np.divide(band_0 - band_1, band_mix)
ndxi[band_mix == 0] = 0
np.seterr(**old_settings)
return ndxi
for itype in NDXI_TYPES:
Image.register(itype, partial(ndxi_image, ndxi_type=itype))
def print_ndxi_statistics(ndxi, option):
"""Prints the ndvi matrix and the, min, max, mean and median."""
print('{o} matrix: '.format(o=option))
print(ndxi)
print('\nMax {o}: {m}'.format(o=option, m=np.nanmax(ndxi)))
print('Mean {o}: {m}'.format(o=option, m=np.nanmean(ndxi)))
print('Median {o}: {m}'.format(o=option, m=np.nanmedian(ndxi)))
print('Min {o}: {m}'.format(o=option, m=np.nanmin(ndxi)))
class NDXI(Feature):
"""
The parent class of the family of NDXI features.
Parameters
----------
window_shapes: list
The window shapes to calculate the feature on.
"""
size = 1
compute = staticmethod(np.mean)
[docs]class NirNDVI(NDXI):
"""
The infrared-green normalized difference vegetation index.
For more information see [2]_.
Parameters
----------
window_shapes: list
The window shapes to calculate the feature on.
Notes
-----
.. [2] https://en.wikipedia.org/wiki/Normalized_difference_vegetation_index
"""
base_image = 'nir_ndvi'
[docs]class RgNDVI(NDXI):
"""
The red-green normalized difference vegetation index.
For more information see [3]_.
Parameters
----------
window_shapes: list
The window shapes to calculate the feature on.
Notes
-----
.. [3] Motohka, T., Nasahara, K.N., Oguma, H. and Tsuchida, S., 2010.
"Applicability of green-red vegetation index for remote sensing of
vegetation phenology". Remote Sensing, 2(10), pp. 2369-2387.
"""
base_image = 'rg_ndvi'
[docs]class RbNDVI(NDXI):
"""
The red-blue normalized difference vegetation index.
For more information see [4]_.
Parameters
----------
window_shapes: list
The window shapes to calculate the feature on.
Notes
-----
.. [4] Tanaka, S., Goto, S., Maki, M., Akiyama, T., Muramoto, Y. and
Yoshida, K., 2007. "Estimation of leaf chlorophyll concentration in
winter wheat [Triticum aestivum] before maturing stage by a newly
developed vegetation index-RBNDVI". Journal of the Japanese
Agricultural Systems Society (Japan).
"""
base_image = 'rb_ndvi'
[docs]class NDSI(NDXI):
"""
The snow cover index.
Parameters
----------
window_shapes: list
The window shapes to calculate the feature on.
"""
base_image = 'ndsi'
[docs]class NDWI(NDXI):
"""
The water cover index.
Parameters
----------
window_shapes: list
The window shapes to calculate the feature on.
"""
base_image = 'ndwi'
[docs]class WVSI(NDXI):
"""
The soil cover index.
Parameters
----------
window_shapes: list
The window shapes to calculate the feature on.
"""
base_image = 'wvsi'