Python 3 compatibility

Author: AllenDowney

code/chap04soln.py

@@ -0,0 +1,133 @@
+"""This file contains code used in "Think DSP",
+by Allen B. Downey, available from greenteapress.com
+
+Copyright 2014 Allen B. Downey
+License: GNU GPLv3 http://www.gnu.org/licenses/gpl.html
+"""
+
+from __future__ import print_function, division
+
+import numpy
+import thinkstats2
+import thinkdsp
+import thinkplot
+
+"""
+Samples used in this file
+
+http://www.freesound.org/people/ciccarelli/sounds/132736/download/
+132736__ciccarelli__ocean-waves.wav
+
+http://www.freesound.org/people/Q.K./sounds/56311/download/
+56311__q-k__rain-06.wav
+
+http://www.freesound.org/people/erkanozan/sounds/51743/download/
+51743__erkanozan__applause.wav
+
+http://www.freesound.org/people/britishpirate93/sounds/162313/download/
+162313__britishpirate93__16-inch-crash.wav
+
+"""
+
+FILENAMES = [
+    '132736__ciccarelli__ocean-waves.wav',
+    '56311__q-k__rain-06.wav',
+    '51743__erkanozan__applause.wav',
+    '162313__britishpirate93__16-inch-crash.wav',
+    '75341__neotone__cymbol-scraped.wav',
+    '181934__landub__applause2.wav',
+    '87594__ohrwurm__occurs-applause.wav',
+    '104466__dkmedic__t-flush.wav',
+    '180929__docquesting__crowd-noise.wav',
+    '695__memexikon__ocarina.wav',
+]
+
+STARTS = [0.6, 2.0, 0.1, 0.3, 0.1, 1.0, 11.0, 4.0, 0.5, 0.5] 
+
+
+
+def segment_spectrum(filename, start, duration=1.0):
+    """Plots the spectrum of a segment of a WAV file.
+
+    Output file names are the given filename plus a suffix.
+
+    filename: string
+    start: start time in s
+    duration: segment length in s
+    """
+    wave = thinkdsp.read_wave(filename)
+    plot_waveform(wave)
+
+    # extract a segment
+    segment = wave.segment(start, duration)
+    segment.ys = segment.ys[:1024]
+    print(len(segment.ys))
+
+    segment.normalize()
+    segment.apodize()
+    spectrum = segment.make_spectrum()
+
+    segment.play()
+
+    # plot the spectrum
+    n = len(spectrum.hs)
+    spectrum.plot()
+
+    thinkplot.save(root=filename,
+                   xlabel='frequency (Hz)',
+                   ylabel='amplitude density')
+
+
+
+def plot_waveform(wave, start=1.30245, duration=0.00683):
+    """Plots a short window from a wave.
+
+    duration: float
+    """
+    segment = wave.segment(start, duration)
+    segment.normalize()
+
+    segment.plot()
+    thinkplot.save(root='waveform',
+                   xlabel='time (s)',
+                   axis=[0, duration, -1.05, 1.05])
+
+
+def process_files():
+    indices = range(len(FILENAMES))
+    #indices = [9]
+
+    for i, (filename, start) in enumerate(zip(FILENAMES, STARTS)):
+        if i in indices:
+            segment_spectrum(filename, start)
+
+
+def make_periodogram(signal, n=1000):
+    """Generates n spectra and plots their average.
+
+    signal: Signal object
+    n: number of spectra to average
+    """
+    specs = []
+    for i in range(n):
+        wave = signal.make_wave(duration=1.0, framerate=1024)
+        spec = wave.make_spectrum()
+        specs.append(spec)
+    
+    spectrum = sum(specs)
+    print(spectrum.estimate_slope())
+    spectrum.plot_power()
+    thinkplot.show(xlabel='frequency (Hz)',
+                   ylabel='power density',
+                   xscale='log',
+                   yscale='log')
+
+
+def main():
+    thinkdsp.random_seed(19)
+    signal = thinkdsp.BrownianNoise()
+    make_periodogram(signal)
+
+
+if __name__ == '__main__':
+    main()

code/thinkdsp.py

@@ -592,7 +592,7 @@ def make_wave(self):
         returns: Wave
         """
         res = []
-        for t, spectrum in sorted(self.spec_map.iteritems()):
+        for t, spectrum in sorted(self.spec_map.items()):
             wave = spectrum.make_wave()
             n = len(wave)