def column_or_1d(y, warn=False):
    shape = np.shape(y)
    if len(shape) == 1:
        return np.ravel(y)
    if len(shape) == 2 and shape[1] == 1:
        if warn:
            warnings.warn("A column-vector y was passed when a 1d array was"
                          " expected. Please change the shape of y to "
                          "(n_samples, ), for example using ravel().",
                          DataConversionWarning, stacklevel=2)
        return np.ravel(y)

    raise ValueError("bad input shape {0}".format(shape))
Ravel column or 1d numpy array, else raises an error
dataset/ETHPy150Open trevorstephens/gplearn/gplearn/skutils/validation.py/column_or_1d