aux_fct.py

### Auxillary Functions ###
from numpy import exp, shape, reshape, sqrt, median
from numpy.random import permutation,randn
from scipy.spatial.distance import squareform, pdist, cdist
import numpy as np
import os
from scipy.io import loadmat

# Median Heuristic method for the RBF Kernel
def get_sigma_median_heuristic(X, is_sparse = False):
    if is_sparse:
        X = X.todense()
    n=shape(X)[0]
    if n>1000:
        X=X[permutation(n)[:1000],:]
    dists=squareform(pdist(X, 'euclidean'))
    median_dist=median(dists[dists>0])
    sigma=median_dist/sqrt(2.)
    return sigma

# Auxillary Dataset Loading 
def load_data(path):
	os.chdir(path)
	mat = loadmat('MISR1.mat')
	array = mat['MISR1']
	x = np.zeros((800, 100, 16))
	y = np.zeros((800,1))
	for i in range(800):
		for j in range(100):
			x[i, j ,:] = array[i * 100 + j, 1:17]
			y[i,:] = array[i * 100 + j, 17]
	return x, y