libscores.py 文件源码

def prior_log_loss(frac_pos, task = 'binary.classification'):
    ''' Baseline log loss. For multiplr classes ot labels return the volues for each column'''
    eps = 1e-15   
    frac_pos_ = sp.maximum (eps, frac_pos)
    if (task != 'multiclass.classification'): # binary case
        frac_neg = 1-frac_pos
        frac_neg_ = sp.maximum (eps, frac_neg)
        pos_class_log_loss_ = - frac_pos * np.log(frac_pos_)
        neg_class_log_loss_ = - frac_neg * np.log(frac_neg_)
        base_log_loss = pos_class_log_loss_ + neg_class_log_loss_
        # base_log_loss = mvmean(base_log_loss)
        # print('binary {}'.format(base_log_loss))
        # In the multilabel case, the right thing i to AVERAGE not sum
        # We return all the scores so we can normalize correctly later on
    else: # multiclass case
        fp = frac_pos_ / sum(frac_pos_) # Need to renormalize the lines in multiclass case
        # Only ONE label is 1 in the multiclass case active for each line
        pos_class_log_loss_ = - frac_pos * np.log(fp)
        base_log_loss = np.sum(pos_class_log_loss_) 
    return base_log_loss

# sklearn implementations for comparison