Python 2到Python 3 Struct Pack问题(Python 2 to Python 3 Struct Pack Issue)

我试图让下面的代码在Python 3中工作。它在Python 2中很好。我已经将xrange s更改为range ，但是此行存在问题： data = ''.join(struct.pack('f', samp) for samp in tone) ：

sequence item 0: expected str instance, bytes found.

我找到了这个答案，但无法解决如何将其应用于我的情况。任何帮助非常感谢。

import math import struct import pyaudio def play_tone(frequency, amplitude, duration, fs, stream): N = int(fs / frequency) T = int(frequency * duration) # repeat for T cycles dt = 1.0 / fs # 1 cycle tone = (amplitude * math.sin(2 * math.pi * frequency * n * dt) for n in xrange(N)) # todo: get the format from the stream; this assumes Float32 data = ''.join(struct.pack('f', samp) for samp in tone) for n in xrange(T): stream.write(data) fs = 48000 p = pyaudio.PyAudio() stream = p.open( format=pyaudio.paFloat32, channels=1, rate=fs, output=True) # play the C major scale scale = [130.8, 146.8, 164.8, 174.6, 195.0, 220.0, 246.9, 261.6] for tone in scale: play_tone(tone, 0.5, 0.75, fs, stream) # up an octave for tone in scale[1:]: play_tone(2*tone, 0.5, 0.75, fs, stream) stream.close() p.terminate()

I'm trying to get the following code to work in Python 3. It is fine in Python 2. I have changed the xranges to range, but there is a problem with this line: data = ''.join(struct.pack('f', samp) for samp in tone):

sequence item 0: expected str instance, bytes found.

I found this answer but couldn't work out how to apply it to my situation. Any help much appreciated.

import math import struct import pyaudio def play_tone(frequency, amplitude, duration, fs, stream): N = int(fs / frequency) T = int(frequency * duration) # repeat for T cycles dt = 1.0 / fs # 1 cycle tone = (amplitude * math.sin(2 * math.pi * frequency * n * dt) for n in xrange(N)) # todo: get the format from the stream; this assumes Float32 data = ''.join(struct.pack('f', samp) for samp in tone) for n in xrange(T): stream.write(data) fs = 48000 p = pyaudio.PyAudio() stream = p.open( format=pyaudio.paFloat32, channels=1, rate=fs, output=True) # play the C major scale scale = [130.8, 146.8, 164.8, 174.6, 195.0, 220.0, 246.9, 261.6] for tone in scale: play_tone(tone, 0.5, 0.75, fs, stream) # up an octave for tone in scale[1:]: play_tone(2*tone, 0.5, 0.75, fs, stream) stream.close() p.terminate()

最满意答案

问题是你要加入的空字符串实际上是一个str实例（一个Unicode字符串），但是你加入到一起的值（你从struct.pack得到的）是bytes实例。 Python 3不会让你像这样混合不同的字符串类型。

改变''为b'' ，它应该工作： data = b''.join(struct.pack('f', samp) for samp in tone)

The issue is that the empty string you're joining on is in fact a str instance (a Unicode string), but the values you're joining together (that you get from struct.pack) are bytes instances. Python 3 doesn't let you mix the different string types together like that.

Change the '' to b'' and it should work: data = b''.join(struct.pack('f', samp) for samp in tone)

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