Source Code for Module gmisclib.hilbert_xform

 1  import Num 
 2   
 3   
 4 -def nextpow2(i): 
 5          j = 1 
 6          while j <= i: 
 7                  j *= 2 
 8          return j 
 9   
10   
11 -def hilbert(x, cutoff): 
12          """This is a Hilbert transform when cutoff=0.""" 
13   
14          xx = Num.asarray(x, Num.Float) 
15          np2 = nextpow2(x.shape[0]) 
16          x = Num.zeros((np2,), Num.Float) 
17          x[:xx.shape[0]] = xx 
18          assert len(x.shape) == 1 
19          n = x.shape[0] 
20          xt = Num.FFT.fft(x) 
21          tmp = Num.arrayrange(n) 
22          f = Num.minimum(tmp, n-tmp) * (1 - 2*Num.greater(tmp, n-tmp)) 
23          window = 1.0 + Num.tanh(f/cutoff) 
24          Num.multiply(xt, window, xt) 
25          return Num.FFT.inverse_fft(xt) 
26   
27   
28   
29  if __name__ == '__main__': 
30          import gpkimgclass 
31          x = gpkimgclass.read('/home/gpk/voicing/mimic.1.1.d') 
32          print "0" 
33          DT = 0.030 
34          y = hilbert(x.d[:,0], DT/x.dt()) 
35          print "F", y.shape 
36          tmp = gpkimgclass.gpk_img({'CDELT2': x.dt(), 'HILBERT_CUTOFF': DT, 
37                                          'BITPIX': -32, 
38                                          'CRPIX2': 0, 'CRVAL2': 0.0}, 
39                  Num.absolute(y)) 
40          tmp.write("foo.d") 
41