python bytes字节换算

def bytes_conversion(number):
    symbols = (‘K‘,‘M‘,‘G‘,‘T‘,‘P‘,‘E‘,‘Z‘,‘Y‘)
    prefix = dict()
    for i,s in enumerate(symbols):
        prefix[s] = 1<<(i+1) *10
        for s in reversed(symbols):
            if int(number) >= prefix[s]:
                value = float(number) / prefix[s]
                return ‘%.2f%s‘ %(value,s)
    return "%sB" %number