Convert little endian string to integer

python numpy wav
Jeffrey Aylesworth picture Jeffrey Aylesworth · Nov 8, 2009 · Viewed 15.5k times · Source

I have read samples out of a wave file using the wave module, but it gives the samples as a string, it's out of wave so it's little endian (for example, \x00).

What is the easiest way to convert this into a python integer, or a numpy.int16 type? (It will eventually become a numpy.int16, so going directly there is fine).

Code needs to work on little endian and big endian processors.

Answer

Ned Batchelder picture Ned Batchelder · Nov 8, 2009

The struct module converts packed data to Python values, and vice-versa.

>>> import struct
>>> struct.unpack("<h", "\x00\x05")
(1280,)
>>> struct.unpack("<h", "\x00\x06")
(1536,)
>>> struct.unpack("<h", "\x01\x06")
(1537,)

"h" means a short int, or 16-bit int. "<" means use little-endian.

Related questions

Python: write a wav file into numpy float array

ifile = wave.open("input.wav") how can I write this file into a numpy float array now?

Read More
Convert pandas dataframe to NumPy array

I am interested in knowing how to convert a pandas dataframe into a NumPy array. dataframe: import numpy as np import pandas as pd index = [1, 2, 3, 4, 5, 6, 7] a = [np.nan, np.nan, np.nan, 0.1, 0.1, 0.1, 0.1] b = [0.2, np.nan, 0.2, 0.2, 0.2, np.nan, np.nan] c = […

Read More
How do I create an empty array/matrix in NumPy?

I can't figure out how to use an array or matrix in the way that I would normally use a list. I want to create an empty array (or matrix) and then add one column (or row) to it at …

Read More