def mean_absolute_error(y_true, y_pred,
                        sample_weight=None,
                        multioutput='uniform_average'):
    """Mean absolute error regression loss

    Read more in the :ref:`User Guide <mean_absolute_error>`.

    Parameters
    ----------
    y_true : array-like of shape = (n_samples) or (n_samples, n_outputs)
        Ground truth (correct) target values.

    y_pred : array-like of shape = (n_samples) or (n_samples, n_outputs)
        Estimated target values.

    sample_weight : array-like of shape = (n_samples), optional
        Sample weights.

    multioutput : string in ['raw_values', 'uniform_average']
        or array-like of shape (n_outputs)
        Defines aggregating of multiple output values.
        Array-like value defines weights used to average errors.

        'raw_values' :
            Returns a full set of errors in case of multioutput input.

        'uniform_average' :
            Errors of all outputs are averaged with uniform weight.


    Returns
    -------
    loss : float or ndarray of floats
        If multioutput is 'raw_values', then mean absolute error is returned
        for each output separately.
        If multioutput is 'uniform_average' or an ndarray of weights, then the
        weighted average of all output errors is returned.

        MAE output is non-negative floating point. The best value is 0.0.

    Examples
    --------
    >>> from sklearn.metrics import mean_absolute_error
    >>> y_true = [3, -0.5, 2, 7]
    >>> y_pred = [2.5, 0.0, 2, 8]
    >>> mean_absolute_error(y_true, y_pred)
    0.5
    >>> y_true = [[0.5, 1], [-1, 1], [7, -6]]
    >>> y_pred = [[0, 2], [-1, 2], [8, -5]]
    >>> mean_absolute_error(y_true, y_pred)
    0.75
    >>> mean_absolute_error(y_true, y_pred, multioutput='raw_values')
    array([ 0.5,  1. ])
    >>> mean_absolute_error(y_true, y_pred, multioutput=[0.3, 0.7])
    ... # doctest: +ELLIPSIS
    0.849...
    """
    y_type, y_true, y_pred, multioutput = _check_reg_targets(
        y_true, y_pred, multioutput)
    output_errors = np.average(np.abs(y_pred - y_true),
                               weights=sample_weight, axis=0)
    if isinstance(multioutput, string_types):
        if multioutput == 'raw_values':
            return output_errors
        elif multioutput == 'uniform_average':
            # pass None as weights to np.average: uniform mean
            multioutput = None

    return np.average(output_errors, weights=multioutput)
dataset/ETHPy150Open scikit-learn/scikit-learn/sklearn/metrics/regression.py/mean_absolute_error/original