m._computeP() -- [utility] Compute the probability matrix (from the internal log-probability matrix)

def _computeP(self):
        """
        m._computeP() -- [utility] Compute the probability matrix (from the internal log-probability matrix)
        """
        P = []
        for i in range(self.width):
            #print i,
            _p = {}
            for L in ACGT: _p[L] = math.pow(2.0,self.logP[i][L])
            P.append(_p)
        #print
        self.P = P