#----------------------------------------------------------------------
def find_int_len(x):
   """Determine the number of characters to the left of the decimal
      point in the float x"""
   count = 0
   y = abs(int(x))
   while y > 0:
      y = y/10
      count = count+1
   if x < 0:
      count = count+1
   return count


#----------------------------------------------------------------------
def create_format(min_val, max_val):
   """Create a format string that can be used to print the upper
      and lower bounds of the bars:  If the return value is s, use

         print s % lower_bound, "--", s % upper_bound, bar_of_xs
   """
   len_min = find_int_len(min_val)
   len_max = find_int_len(max_val)
   if len_min > len_max:
      field_width = len_min+2  # For decimal and one place to right of decimal
   else:
      field_width = len_max+2  # For decimal and one place to right of decimal
   format_s = '%' + str(field_width) + '.1f'
   return format_s