multivac61

# swampme.sh
# Create a 16GB swap space in  current file system

dd if=/dev/zero of=/var/myswap bs=1M count=16384
mkswap /var/myswap
swapon /var/myswap

echo "/var/myswap   swap   swap   defaults  0 0" >> /etc/fstab

multivac61

def freq_from_CEPS(sig, fs):  
    N = len(sig)
    windowed = sig * blackmanharris(N)

    spectrum = np.fft.rfft(windowed, fs) 
    spectrum[spectrum == 0] = EPSILON
    log_spectrum = np.log(np.abs(spectrum))
    ceps = np.fft.irfft(log_spectrum)

    start = int(fs / HIGH_FREQ)

multivac61

def freq_from_HPS(sig, fs):
    N = len(sig)
    windowed = sig * blackmanharris(N)
    X = np.abs(rfft(windowed))
    
    hps = X
    n_harmonic_partials = 6
    for h in range(2, n_harmonic_partials):
        # downsample the spectra
        dec = scipy.signal.decimate(X, h)

multivac61

def freq_from_FFT(sig, fs):
    # Compute Fourier transform of windowed signal
    N = len(sig)
    windowed = sig * blackmanharris(N)
    X = np.abs(np.fft.rfft(windowed))
    
    # Find the peak and interpolate
    i = np.argmax(abs(X)) # Just use this for less-accurate, naive version
    X[X == 0] = epsilon   # Circumvent division by 0

multivac61

def freq_from_AC(sig, fs):
    corr = np.correlate(sig, sig, mode='full')
    corr = corr[corr.size/2:]
    
    # Find the first low point
    d = diff(corr)

    # first point with pos. 
    start = find(d > 0)

multivac61

def freq_from_ZCR(sig, fs):
    # Find all indices right before a rising-edge zero crossing
    indices = find((sig[1:] >= 0) & (sig[:-1] < 0))

    crossings = interpolate(indices, sig)

    return fs / np.mean(np.diff(crossings))

multivac61

# A script to remind me how to check if an
# array contains a zero. If it does
# we should mask it with some tiny number

from sys import float_info

epsilon = float_info.epsilon

# X is input variable, f.x. FFT
X[X == 0] = epsilon

multivac61

class KnightsTour():
    '''Knights Tour using Warnsdorf's rule as heuristics'''

    def __init__(self, N, start_point=(0,0)):
        self.N             = N
        self.initial_state = (start_point, )
        # all relative moves expressed as displacement in 2D
        self._actions      = [(1,2), (1,-2), (2,1), (2,-1),\
                              (-1,2), (-1,-2), (-2,1), (-2,-1)]

multivac61

    def _viterbi(self, observations):
        '''Generate the most likely sequence of words given the observations'''
        transitions = self.transition_prob; emissions = self.emission_prob

        V = {};    V[(0, X0)] = log10(1)    # initial probabilities
        path = {}; path[X0] = [X0]          # path to most likely seq
        
        current_words = [[] for i in range(len(observations)+1)]
        current_words[0] = [X0] # list of words that have an entry in bigram table

multivac61

'This is an example of list comprehension control variables being leaked to their outer scope'

for i in range(10):
    a = [i for i in range(43)]
    print i # will print 42 every time!