dualbooting

py
def w1_tree_split_data_left(X, Y, feature_index, split_value):
    """Split the data `X` and `Y`, at the feature indexed by `feature_index`.
    If the value is less than `split_value` then return it as part of the left group.
    
    # Arguments
        X: np.array of size `(n_objects, n_in)`
        Y: np.array of size `(n_objects, 1)`
        feature_index: index of the feature to split at 
        split_value: value to split between
    # Output
        (XY_left): np.array of size `(n_objects_left, n_in + 1)`
    """
    X_left, Y_left = None, None
    XY_left = []
    for row in X, Y:
        if row[feature_index] < split_value:
            XY_left = X.append(Y)
    return XY_left

.append()

X + Y

[*X, *Y]

X

Y