hparray: An introduction


The motivation behind the creation of this package was performing common tasks on a numpy ndarray for hyperspectral data which could be better served by extending the ndarray type with added functionality for hyperspectral data. This package provides just that, a hparray type that subclasses ndarray and adds further functionality. An advantage over other packages is that it the hparray object can still be used as a normal numpy array for other tasks.

Processing data

The hyperspectral data is stored and processed using hparray.


Note that the array should be formatted in the following order:

(spatial, spectral)

i.e. the spatial dimensions should proceed the spectral dimension/channels. As an example, if our hyperspectral dataset has dimensions of x=10, y=10, z=10 and channels=100 then the array should be formatted as:

(10, 10, 10, 100)

Below is an example of instantiating a hparray object with a 4d random numpy array.

import numpy as np
import hypers as hp

test_data = np.random.rand(40, 40, 4, 512)
X = hp.array(test_data)


The hparray object has several useful attributes and methods for immediate analysis:


Note that as hparray subclasses numpy’s ndarray, all the usual methods and attributes in a numpy array can also be used here.

# Data properties:
X.shape                            # Shape of the hyperspectral array
X.ndim                             # Number of dimensions
X.nfeatures                        # Size of the spectral dimension/channels
X.nsamples                         # Total number of pixels (samples)
X.nspatial                         # Shape of the spatial dimensions

# To access the mean image/spectrum of the dataset:

# To access the image/spectrum in a specific pixel/spectral range:
X.spectrum[10:20, 10:20, :, :]     # Returns spectrum within chosen pixel range
X.image[..., 100:200]              # Returns image averaged between spectral bands

# To view and interact with the data:
X.plot(backend='pyqt')                           # Opens a hyperspectral viewer

To view the full list of methods and attributes that the Process class contains, see hparray.