src/dunshire/errors.py

   1 """
   2 Errors that can occur when solving a linear game.
   3 """
   4
   5 from cvxopt import matrix
   6
   7
   8 def _pretty_print_dict(dictionary):
   9     """
  10     Return a pretty-printed string representation of a dictionary
  11     containing CVXOPT matrices.
  12     """
  13     result = ''
  14     for (key, value) in dictionary.items():
  15         if isinstance(value, matrix):
  16             # Display matrices on their own lines, indented.
  17             result += '  {:s}:'.format(key)
  18             colvec = '\n{!s}'.format(value)
  19             result += '\n    '.join(colvec.splitlines())
  20             result += '\n'
  21         else:
  22             result += '  {:s}: {!s}\n'.format(key, value)
  23
  24     return result
  25
  26
  27 class GameUnsolvableException(Exception):
  28     """
  29     Every linear game has a solution (this follows from a general
  30     min-max theorem). If we can't solve the conic program associated
  31     with a linear game, then something is wrong with either the model of
  32     the input.
  33     """
  34     def __init__(self, solution_dict):
  35         """
  36         Create a new GameUnsolvableException object.
  37
  38         INPUT:
  39
  40         - ``solution_dict`` -- the solution dictionary returned from the
  41           cone program.
  42
  43         """
  44         super().__init__()
  45         self._solution_dict = solution_dict
  46
  47
  48     def __str__(self):
  49         tpl = 'Solution failed with result "{:s}."\n' \
  50               'CVXOPT returned:\n{!s}'
  51         return tpl.format(self._solution_dict['status'],
  52                           _pretty_print_dict(self._solution_dict))