missingno.py 文件源码

def _calculate_geographic_nullity(geo_group, x_col, y_col):
    """
    Helper method which calculates the nullity of a DataFrame. Factored out of and used within `geoplot`.
    """
    # Aggregate by point and fetch a list of non-null coordinate pairs, which is returned.
    point_groups = geo_group.groupby([x_col, y_col])
    points = [point for point in point_groups.groups.keys() if pd.notnull(point[0]) and pd.notnull(point[1])]
    # Calculate nullities by location, then take their average within the overall feature.
    counts = np.sum(point_groups.count().values, axis=1)
    entries = point_groups.size()
    width = len(geo_group.columns)
    # Remove empty (NaN, NaN) points.
    if len(entries) > 0:  # explicit check to avoid a Runtime Warning
        geographic_nullity = np.average(1 - counts / width / entries)
        return points, geographic_nullity
    else:
        return points, np.nan