PythonGitHub/sigfig.py at master · chrisjcc/PythonGitHub · GitHub

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#!/usr/bin/python

############################################
#                                          #
#   Write by: Christian Contreras-Campana  #
#   email: christian.contreras@desy.de     #
#   Date: 05.08.2016                       #
#                                          #
############################################

'''Module provides functionality for working with significant figures.'''
import types, re, string

epat = re.compile(r'^([^e]+)e(.+)$')

def round_sig(x, n):
   '''Round floating point x to n significant figures'''
   if type(n) is not types.IntType:
      raise TypeError, "n must be an integer"
   try:
      x = float(x)
   except:
      raise TypeError, "x must be a floating point object"
   form = "%0." + str(n-1) + "e"
   st = form % x
   num,expo = epat.findall(st)[0]
   expo = int(expo)
   fs = string.split(num,'.')
   if len(fs) < 2:
      fs = [fs[0],""]
   if expo == 0:
      return num
   elif expo > 0:
      if len(fs[1]) < expo:
         fs[1] += "0"*(expo-len(fs[1]))
      st = fs[0]+fs[1][0:expo]
      if len(fs[1][expo:]) > 0:
         st += '.'+fs[1][expo:]
      return st
   else:
      expo = -expo
      if fs[0][0] == '-':
         fs[0] = fs[0][1:]
         sign = "-"
      else:
         sign = ""
      return sign+"0."+"0"*(expo-1)+fs[0]+fs[1]