python类fft()的实例源码

def call_spec():
    global y,NFFT,Fsamp,Fcentre,foverlap,detrend,_window, _type, fmod, chan_name, diag_name
    print len(y), NFFT,foverlap, _type, fmod
    ax = pl.subplot(111)
    z=_window(y)
    if _type=='F': 
        shot=callback.get_shot()
        print("shot=%d") % shot
        data = device.acq.getdata(shot, diag_name)    
        if chan_name=='':
            try:
                ch=data.channels
                print("Choosing from", [chn.name for chn in ch])
                name=ch[channel_number].name
            except:
                print "Failed to open channel database - try mirnov_1_8"
                name='mirnov_1_8'
                name='mirnov_linear_2'
        else:        
            name=chan_name

#        data = pyfusion.load_channel(shot,name)
#        data = pyfusion.acq.getdata(shot_number, diag_name)    
        if data==None: return(False)

        if _window==local_none: windowfn=pl.window_none
#        else: windowfn=pl.window_hanning
        elif _window==local_hanning: windowfn=pl.window_hanning
        else: windowfn=_window(arange(NFFT))
        clim=(-60,20)   # eventually make this adjustable
# colorbar commented out because it keeps adding itself
        data.plot_spectrogram(NFFT=NFFT, windowfn=windowfn, noverlap=foverlap*NFFT, 
                              channel_number=channel_number)
#                         colorbar=True, clim=clim)
#        colorbar() # used to come up on a separate page, fixed, but a little clunky - leave for now

        return(True)
    elif _type == 'T':
# some matplotlib versions don't know about Fc
        pl.specgram(z*y, NFFT=NFFT, Fs=Fsamp, detrend=detrend,
#                 window = _window
                 noverlap=foverlap*NFFT, cmap=cmap)
    elif _type == 'L':
        pl.plot(20*log10(abs(fft.fft(y*z))))
    elif _type == 'W':
        pl.plot(z)
    elif _type =='C':
        pl.plot(hold=0)
    else: raise ' unknown plot type "' + _type +'"'
#    pl.show()

# ------  END of call_spec