import math import string class size( long ): """ define a size class to allow custom formatting format specifiers supported : em : formats the size as bits in IEC format i.e. 1024 bits (128 bytes) = 1Kib eM : formats the size as Bytes in IEC format i.e. 1024 bytes = 1KiB sm : formats the size as bits in SI format i.e. 1000 bits = 1kb sM : formats the size as bytes in SI format i.e. 1000 bytes = 1KB cm : format the size as bit in the common format i.e. 1024 bits (128 bytes) = 1Kb cM : format the size as bytes in the common format i.e. 1024 bytes = 1KB """ def __format__(self, fmt): # is it an empty format or not a special format for the size class if fmt == "" or fmt[-2:].lower() not in ["em","sm","cm"]: if fmt[-1].lower() in ['b','c','d','o','x','n','e','f','g','%']: # Numeric format. return long(self).__format__(fmt) else: return str(self).__format__(fmt) # work out the scale, suffix and base factor, suffix = (8, "b") if fmt[-1] in string.lowercase else (1,"B") base = 1024 if fmt[-2] in ["e","c"] else 1000 # Add the i for the IEC format suffix = "i"+ suffix if fmt[-2] == "e" else suffix mult = ["","K","M","G","T","P"] val = float(self) * factor i = 0 if val < 1 else int(math.log(val, base))+1 v = val / math.pow(base,i) v,i = (v,i) if v > 0.5 else (v*base,i-1) # Identify if there is a width and extract it width = "" if fmt.find(".") == -1 else fmt[:fmt.index(".")] precis = fmt[:-2] if width == "" else fmt[fmt.index("."):-2] # do the precision bit first, so width/alignment works with the suffix t = ("{0:{1}f}"+mult[i]+suffix).format(v, precis) return "{0:{1}}".format(t,width) if width != "" else t if __name__ == "__main__": # Example usages # You can use normal format spcifiers as expected - just use the correct the presentation type (instead of f, e, G etc) # and cast the integer byte count to type size. # Example format specifications print "{0:.1f}".format(4386) # output - 4386.0 print "{0:.1f}".format(size(4386)) # output 4386.0 - default numeric presentations respected. print "{0:.2eM}".format(size(86247)) # output 84.23KiB - base 1024 print "{0:.2sM}".format(size(86247)) # output 86.25KB - base 1000 print "{0:.2cM}".format(size(86247)) # output 84.23KB - base 1024 print "{0:.2cm}".format(size(86247)) # output 0.66Mb - base 1024 in bits.