'Train on data (list of arrays n*dim).
Labels are optional, default is 0...n-1.'

def train(self, data, labels=None):

    if (labels == None):
        labels = range(len(data))
    self.labels = labels
    self.n = len(labels)
    for c in data:
        self.mean.append(mean(c, axis=0))
        self.var.append(var(c, axis=0))
