title: my python is confusing the minus with dash sign
body: <p>I am trying to run the following python with <em>" python get_timestamp.py -f gsham_input.xvg -1 −0.1348  -2 −0.1109"</em>. However, it seems that the python is mistaking the minus sign before the decimals with the dash sign and shows this error: "File "get_timestamp.py", line 21, in 
      value1 = float(arg)
  ValueError: invalid literal for float(): −0.1348
  "
  Could you please help me know how to resolve it?</p>
  
  <p>Thanks.</p>
  
  <pre><code>#!/usr/bin/env python
  
  """
  Given two values, looks in a 3 column-file (output of sham.pl)
  which time frame matches closest.
  """
  
  import sys
  
  USAGE = "USAGE: get_timestamp.py -f &lt;sham output&gt; -1 &lt;value 1&gt; -2 &lt;value 2&gt;\n"
  
  # Parse arguments
  read_input, read_value1, read_value2 = False, False, False
  input_file, value1, value2 = None, None, None
  for arg in sys.argv[1:]:
      if read_input:
          read_input = False
          input_file = arg
      elif read_value1:
          read_value1 = False
          value1 = float(arg)
      elif read_value2:
          read_value2 = False
          value2 = float(arg)
      if arg[0] == "-":
          if arg == "-f":
              read_input = True
              continue
          elif arg == "-1":
              read_value1 = True
              continue
          elif arg == "-2":
              read_value2 = True
          else:
              print USAGE
              sys.stderr.write('ERROR: Option not recognized: %s\n' %arg)
              sys.exit(1)
  
  if not input_file:
      print USAGE
      sys.stderr.write('ERROR: You forgot to provide an input file.\n')
      sys.exit(1)
  
  # Open sham output
  x_values, y_values, time_values = [], [], []
  fhandle = open(input_file)
  for line in fhandle:
      if line[0] != "#" and len(line.split()) == 3:
          t,x,y = line.split()
          x_values.append(float(x))
          y_values.append(float(y))
          time_values.append(float(t))
  fhandle.close()
  
  def find_common_frame(min_x, min_y):
      for xval in min_x:
          xframe = xval[0]
          for yval in min_y:
              yframe = yval[0]
              if xframe == yframe:
                  return (xframe, xval[1], yval[1])
      return (None, None, None)
  
  # If you cannot find anything, try increasing the nval variable
  nval = 50
  min_x = sorted(enumerate(x_values), key=lambda x: abs(x[1]-value1))[:nval]
  min_y = sorted(enumerate(y_values), key=lambda x: abs(x[1]-value2))[:nval]
  
  frame, x, y = find_common_frame(min_x, min_y)
  
  if not frame:
      print "No timestamp found.."
      sys.exit(0)
  print "## T = %s (%s, %s)" %(time_values[frame], x, y)
  </code></pre>