python - 如何按索引对熊猫数据框求和

Question

我有一堆带有日期时间索引和返回的数据框。我必须创建一个唯一的数据框，按索引对数据框的所有返回值求和。

DATAFRAME A
Date
12-12-2004       5
13-12-2004       7

DATAFRAME B
Date
12-12-2004       6
13-12-2004       -3

DATAFRAME A+B
Date
12-12-2004       11
13-12-2004       4

基本上就是这个概念。所以，输入代码：

total_daily_returns = pd.DataFrame()

for pair in range(0, 10):
    returns_pair = pd.DataFrame()
    returns_pair['cum_daily_return'] = signals['column1']
    returns_pair['cumulative_returns'] = returns_pair['cum_daily_return'].cumsum()

    total_daily_returns = total_daily_returns + (
        returns_pair.cumulative_returns)

    print(total_daily_returns)

我希望它会起作用，而不是我得到：

    Empty DataFrame
Columns: [2004-06-28 00:00:00, 2004-06-29 00:00:00, 2004-06-30 00:00:00, 2004-07-01 00:00:00, 2004-07-02 00:00:00, 2004-07-05 00:00:00, 2004-07-06 00:00:00, 2004-07-07 00:00:00, 2004-07-08 00:00:00, 2004-07-09 00:00:00, 2004-07-12 00:00:00, 2004-07-13 00:00:00, 2004-07-14 00:00:00, 2004-07-15 00:00:00, 2004-07-16 00:00:00, 2004-07-19 00:00:00, 2004-07-20 00:00:00, 2004-07-21 00:00:00, 2004-07-22 00:00:00, 2004-07-23 00:00:00, 2004-07-26 00:00:00, 2004-07-27 00:00:00, 2004-07-28 00:00:00, 2004-07-29 00:00:00, 2004-07-30 00:00:00, 2004-08-02 00:00:00, 2004-08-03 00:00:00, 2004-08-04 00:00:00, 2004-08-05 00:00:00, 2004-08-06 00:00:00, 2004-08-09 00:00:00, 2004-08-10 00:00:00, 2004-08-11 00:00:00, 2004-08-12 00:00:00, 2004-08-13 00:00:00, 2004-08-16 00:00:00, 2004-08-17 00:00:00, 2004-08-18 00:00:00, 2004-08-19 00:00:00, 2004-08-20 00:00:00, 2004-08-23 00:00:00, 2004-08-24 00:00:00, 2004-08-25 00:00:00, 2004-08-26 00:00:00, 2004-08-27 00:00:00, 2004-08-30 00:00:00, 2004-08-31 00:00:00, 2004-09-01 00:00:00, 2004-09-02 00:00:00, 2004-09-03 00:00:00, 2004-09-06 00:00:00, 2004-09-07 00:00:00, 2004-09-08 00:00:00, 2004-09-09 00:00:00, 2004-09-10 00:00:00, 2004-09-13 00:00:00, 2004-09-14 00:00:00, 2004-09-15 00:00:00, 2004-09-16 00:00:00, 2004-09-17 00:00:00, 2004-09-20 00:00:00, 2004-09-21 00:00:00, 2004-09-22 00:00:00, 2004-09-23 00:00:00, 2004-09-24 00:00:00, 2004-09-27 00:00:00, 2004-09-28 00:00:00, 2004-09-29 00:00:00, 2004-09-30 00:00:00, 2004-10-01 00:00:00, 2004-10-04 00:00:00, 2004-10-05 00:00:00, 2004-10-06 00:00:00, 2004-10-07 00:00:00, 2004-10-08 00:00:00, 2004-10-11 00:00:00, 2004-10-12 00:00:00, 2004-10-13 00:00:00, 2004-10-14 00:00:00, 2004-10-15 00:00:00, 2004-10-18 00:00:00, 2004-10-19 00:00:00, 2004-10-20 00:00:00, 2004-10-21 00:00:00, 2004-10-22 00:00:00, 2004-10-25 00:00:00, 2004-10-26 00:00:00, 2004-10-27 00:00:00, 2004-10-28 00:00:00, 2004-10-29 00:00:00, 2004-11-01 00:00:00, 2004-11-02 00:00:00, 2004-11-03 00:00:00, 2004-11-04 00:00:00, 2004-11-05 00:00:00, 2004-11-08 00:00:00, 2004-11-09 00:00:00, 2004-11-10 00:00:00, 2004-11-11 00:00:00, 2004-11-12 00:00:00, ...]
Index: []

有人可以帮我得到我所缺少的吗？

标签： pythonpandas