':param C: The correction constant.  The value of the correction
feature is based on this value.  In particular, its value is
``C - sum([v for (f,v) in encoding])``.
:seealso: ``BinaryMaxentFeatureEncoding.__init__``'

def __init__(self, labels, mapping, unseen_features=False, alwayson_features=False, C=None):

    BinaryMaxentFeatureEncoding.__init__(self, labels, mapping, unseen_features, alwayson_features)
    if (C is None):
        C = (len(set((fname for (fname, fval, label) in mapping))) + 1)
    self._C = C
