accumulating rows in chronologic order in datafame b until reaching approximately the values in dataframe a in chronologic order

Question

I got two dataframes: df_a and df_b. both dataframes indexes are datetime in the following format and are already sorted in the right order: 2022-02-28 07:00:00. df_a['Kies'] has bigger values than df_b['Produzierte Menge'].

I would like to write a function that accumulates the values of df_b['Produzierte Menge'], until it is approximately as big as df_a['Kies']. As soon as it reaches the value approximately, the next value of df_a['Kies'] should be reached by accumulating the values of df_b['Produzierte Menge'], and so on.

Following conditions need to be considered:

• the values of data_produktionsstatistik_produktion['Produzierte Menge'] can only be accumulated in the right time order
• once a value of data_produktionsstatistik_produktion['Produzierte Menge'] has been included in the accumulation, it can not be used anymore. For example: To reach the first value of df_a['Kies'] the first five rows have been accumulated. To reach the second value of df_a['Kies'] the accumulatioin should start at the sixth row -only compare values that happen at the same day! no accumulation of multiple days

THIS IS MY CODE:

def match_daily_values(df_a, df_b):
    result_rows = []

    for date, target_kies in df_a.iterrows():
        target_kies_value = target_kies['Kies']
        cumulative_produzierte_menge = 0

        for prod_date, produzierte_menge in df_b.iterrows():
            if prod_date.date() != date.date():
                continue

            cumulative_produzierte_menge += produzierte_menge['Produzierte Menge']
            result_rows.append({'Date': date, 'Cumulative_Produzierte_Menge': cumulative_produzierte_menge, 'Target_Kies': target_kies_value})

            if cumulative_produzierte_menge >= target_kies_value:
                break

    result_df = pd.DataFrame(result_rows)
    return result_df

result_df = match_daily_values(df_a, df_b)

MY PROBLEM:

When the value is approximately reached of df_a['Kies'], the accumulation start always at the first value of the respective day, and not with the following value of the last accumulated value.