Exemplos de PyGFT em Python

Exemplo n.º 1

def simpleExample():
	# Create a signal
	N = 256
	signal = numpy.zeros(N,numpy.complex128)
	# Make our signal 1 in the middle, zero elsewhere
	signal[N/2] = 1.0
	# plot our signal
	pylab.figure()
	pylab.plot(abs(signal))
	# Do the GFT on the signal
	SIGNAL = gft.gft1d(signal,'gaussian')
	# plot the magnitude of the signal
	pylab.figure()
	pylab.plot(abs(SIGNAL),'b')
	
	# get the partitions
	partitions = gft.partitions(N)
	# for each partition, draw a line on the graph.  Since the partitions only indicate the
	# positive frequencies, we need to draw partitions on both sides of the DC
	for i in partitions[0:len(partitions)/2]:
		pylab.axvline((N/2+i),color='r',alpha=0.2)
		pylab.axvline((N/2-i),color='r',alpha=0.2)
		
	# finally, interpolate the GFT spectrum and plot a spectrogram
	pylab.figure()
	pylab.imshow(abs(gft.gft1dInterpolateNN(SIGNAL)))

Exemplo n.º 2

def gaussianWindow(signal,t,k):
	l = len(signal)
	x = numpy.arange(0,1,1./l).astype(numpy.complex64)
	win = 1*numpy.abs(k)/numpy.sqrt(2*numpy.pi)*numpy.e**(-(x-0.5)**2*numpy.abs(k)**2/2.)
	win = win/(numpy.sum(win)/l)
	win = gft.shift(win,-l/2)
	win = gft.shift(win,t)
	return win

Exemplo n.º 3

def plot2D(image,window,figTitle=None):
	N = numpy.shape(image)[0]
	transform = gft.gft2d(image,window)
	pylab.figure()
	pylab.subplot(121)
	if figTitle: pylab.title(figTitle)
	pylab.imshow(image.real)

	pylab.subplot(122)
	pylab.imshow(abs(transform))
	partitions = gft.partitions(N)
	for i in partitions[0:len(partitions)/2]:
		pylab.axvline((N/2+i),color='r',alpha=0.2)
		pylab.axvline((N/2-i),color='r',alpha=0.2)
		pylab.axhline((N/2+i),color='r',alpha=0.2)
		pylab.axhline((N/2-i),color='r',alpha=0.2)
	pylab.axis((0,N,0,N))

Exemplo n.º 4

def transform2D():
	N = 256
	image = numpy.zeros((N,N))

	image1 = numpy.copy(image); image1[N/2,N/2] = 1.0
	plot2D(image1,'gaussian','Transform of A 2D Delta: Gaussian Window')
	plot2D(image1,'box','Transform of A 2D Delta: Boxcar Window')

	image2 = dist(image); image2 /= numpy.max(numpy.ravel(numpy.abs(image2))); image2 = numpy.cos(2*numpy.pi*96*image2)
	plot2D(image2,'gaussian','Transform of A Circularly Symmetric Cosine: Gaussian Window')
	plot2D(image2,'box','Transform of A Circularly Symmetric Cosine: Boxcar Window')

	image3 = dist(image); image3 /= numpy.max(numpy.ravel(numpy.abs(image3))); image3 = numpy.cos(2*numpy.pi*48*image3)*gaussian2D(image3,8)
	image3 = gft.shift(image3,-N/4,-N/4)
	image3 += gft.shift(image2*gaussian2D(image3,8),N/4,N/4)
	plot2D(image3,'gaussian','Transform of A Gaussian Modulated Circularly Symmetric Cosine: Gaussian Window')
	plot2D(image3,'box','Transform of A Gaussian Modulated Circularly Symmetric Cosine: Boxcar Window')

Exemplo n.º 5

def plot1D(signal,window,figTitle=None):
	N = len(signal)
	x = numpy.arange(0,1,1./N)
	transform = gft.gft1d(signal,window)
	pylab.figure()
	pylab.subplot(211)
	if figTitle: pylab.title(figTitle)
	pylab.plot(x,signal.real,'b')
	pylab.plot(x,signal.imag,'b--')
	ax = pylab.axis()

	pylab.subplot(212)
	pylab.plot(x,transform.real,'b')
	pylab.plot(x,transform.imag,'g--')
	partitions = gft.partitions(N)
	for i in partitions[0:len(partitions)/2]:
		pylab.axvline((N/2+i)/float(N),color='r',alpha=0.2)
		pylab.axvline((N/2-i)/float(N),color='r',alpha=0.2)