Python Formatting Functions

format.py

import re
import datetime
import math

def format_timeinterval(start, end=None):
   if not end:
       end = datetime.now()
   return format_timedelta(end - start)

def format_secondsdelta(seconds):
   """"""Useful for database time differences""""""
   return format_timedelta(datetime.timedelta(0, seconds, 0))
  
def format_timedelta(td):
   if td.days > 365:
       return _format_num(td.days / 365.0, 'yrs')
   if td.days > 30:
       return _format_num(td.days / 30.0, 'mos')
   if td.days > 7:
       return _format_num(td.days / 7.0, 'wks')
   if td.days > 0:
       return _format_num(td.days + td.seconds / (60.0 * 60.0 * 24.0), 'days')
   if td.seconds > 3600:
       return _format_num(td.seconds / 3600.0, 'hrs')
   if td.seconds > 60:
       return _format_num(td.seconds / 60.0, 'min')
   if td.seconds > 0:
       return _format_num(td.seconds + td.microseconds / 1000000.0, 'sec')
   return _format_num(td.microseconds / 1000.0, 'msec')

def _format_num(val, units):
   s = ""%.1f %s"" % (val, units)
   # HACK works but ugly
   return s.replace('.0 ', ' ')
      
def commas(value):
   return """".join(commafy(value))

def commafy(s):
   if s.startswith('-'):
       s = s[1:]
       yield ""-""
   pieces = str(s).split(""."")
   n = len(pieces[0])
   for i in range(0, n):
       if (n - i) % 3 or not i:
           yield pieces[0][i]
       else:
           yield "",""
           yield pieces[0][i]
   if len(pieces) > 1:
       yield ""."" + pieces[1]

# TODO make this fancy like C# formatting...
def format(value, fmt):
   """"""Format a numeric value supporting things
   like commas, parens for negative values and
   special cases for zeros. Format is:

   'n[cpzZ]%'  ex: '2c', '0cpz', '1%'
  
   n - number of decimals
   c - use commas
   p - wrap negative numbers in parenthesis
   z - use a ' ' for zero values
   Z - use a '-' for zero values
   K - convert to thousands and add 'K' suffix
   M - convert to millions and add 'M' suffix
   B - convert to billions and add 'B' suffix
   S - convert to shorter of KMB formats
   % - scale by 100 and add a percent sign at the end (unless z/Z)
   """"""
   # first ensure we have a reasonable value
   try:
       value = float(value)
   except:
       return value or ''
   # now format it
   try:
       m = re.match(r'^(\d)[cpzZKMBS%]{0,4}$', fmt)
       if not m:
           return value
       # handle zero specially, if requested
       if value == 0:
           if 'z' in fmt:
               return ''
           elif 'Z' in fmt:
               return '-'
       # scale if using %, K, M or B formats
       suffix = ''
       factor = { '%': 1e2, 'K': 1e-3, 'M': 1e-6, 'B': 1e-9 }
       for k in factor.keys():
           if k in fmt:
               suffix = k
               value *= factor[k]
               break                   
       # use parens for negative values
       parens = False
       if 'p' in fmt and value < 0:
           value = -value
           parens = True
       # format the number to the specified number of decimal places
       s = '%%.%sf' % m.group(1)
       val = s % value
       # fix up with commas
       if 'c' in fmt:
           val = commas(val)
       # wrap in parens
       if parens:
           val = '(%s)' % val
       elif 'p' in fmt:
           # pad positive numbers so the last digit lines up better
           val = '%s' % val           
       val += suffix
       return val
   except Exception, e:
       return value or ''