def points_per_group(points, grouper_col, ct_col="Núm. Pts."):
    """Count the points in the given group

    Parameters
    ----------
    points : pandas DataFrame
        Point observations
    grouper_col : str
        Column in `points` that you want to use to group, usually 'geo_field' or similar
    ct_col : str, optional
        Name to give the new column

    Returns
    -------
    df : pandas DataFrame
        Points grouped and counted according to the grouper_col    
    """
    df = (
        points.groupby(grouper_col)
        .size()
        .reset_index(name=ct_col)
        .set_index(grouper_col)
    )
    df.index.rename("Id", inplace=True)
    return df