def explode_user_titles()

in src/rime/util/__init__.py [0:0]

• 15 lines of code
• 6 McCabe index (conditional complexity)

def explode_user_titles(user_hist, item_titles, gamma=0.5, min_gamma=0.1, pad_title='???'):
    """ explode last few user events and match with item titles;
    return splits and discount weights; empty user_hist will be turned into a single pad_title. """

    keep_last = int(np.log(min_gamma) / np.log(np.clip(gamma, 1e-10, 1 - 1e-10))) + 1  # default=4

    explode_titles = pd.Series([x[-keep_last:] for x in user_hist.values]).explode() \
        .to_frame('ITEM_ID').join(item_titles.to_frame('TITLE'), on='ITEM_ID')['TITLE']
    explode_titles = pd.Series(
        [x if not na else pad_title for x, na in
         zip(explode_titles.tolist(), explode_titles.isna().tolist())],
        index=explode_titles.index)

    splits = np.where(
        np.array(explode_titles.index.values[1:]) != np.array(explode_titles.index.values[:-1])
    )[0] + 1

    weights = np.hstack([gamma ** (np.cumsum(x) - np.sum(x))  # -2, -1, 0
                        for x in np.split(np.ones(len(explode_titles)), splits)])
    weights = np.hstack([x / x.sum() for x in np.split(weights, splits)])

    return explode_titles.values, splits, weights