Python function to convert a human-readable byte string (e.g. 2G, 10GB, 30MB, 20KB) to a number of bytes

human_readable_to_bytes.py

# stolen from https://stackoverflow.com/questions/354038/how-do-i-check-if-a-string-is-a-number-float
def is_number(s):
   """
   tries to convert to float and returns true if it works
   """
    try:
        float(s)
        return True
    except ValueError:
        return False

def human_readable_to_bytes(size):
    """
    Given a human-readable byte string (e.g. 2G, 10GB, 30MB, 20KB),
    return the number of bytes.  Will return 0 if the argument has
    unexpected form.
    maub: I've made this new version for py3 and for abbreviations in the
    real world, that might use floats (in my case: df under linux)
    """
    if size[-1] == 'B':
        size = size[:-1]
    if is_number(size):
        bytes = float(size)
    else:
        bytes = size[:-1]
        unit = size[-1]
        if is_number(bytes):
            bytes = float(bytes)
            if unit == 'G':
                bytes *= 1073741824
            elif unit == 'M':
                bytes *= 1048576
            elif unit == 'K':
                bytes *= 1024
            else:
                bytes = 0
        else:
            bytes = 0
    return int(bytes)