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python - 如何根据 Python 中的条件将另一个数据帧中的值分配给当前数据帧？

问题描述

我想根据 DatetimeIndex 条件将数据帧中的值分配给另一个数据帧。

我有这个数据框：（第一）

date                importance
2006-12-05 10:35:00     HIGH
2006-12-13 02:40:00     LOW

这个数据框：（第二）

index                     value
2006-12-05 08:03:01.985    6
2006-12-05 08:11:34.130    7
2006-12-05 08:20:05.959    6
2006-12-05 08:28:38.104    6
2006-12-05 08:37:02.995    6
2006-12-05 08:45:35.140    5
2006-12-05 08:54:06.969    6
2006-12-05 09:02:59.928    6
2006-12-05 09:11:32.072    6
2006-12-05 09:20:03.901    6
2006-12-05 09:28:36.046    5
2006-12-05 09:37:00.937    5
2006-12-05 09:45:33.082    6
2006-12-05 09:54:04.911    6
2006-12-05 10:02:04.889    6
2006-12-05 10:10:37.034    5
2006-12-05 10:19:08.863    6
2006-12-05 10:27:41.008    5
2006-12-05 10:36:04.953    5
2006-12-05 10:44:37.098    5
.
.
.
2006-12-13 02:06:00.898    1
2006-12-13 02:14:33.043    1
2006-12-13 02:23:04.872    1
2006-12-13 02:31:03.904    1
2006-12-13 02:39:36.048    1
2006-12-13 02:48:07.878    2
2006-12-13 02:56:40.022    5
2006-12-13 03:05:04.914    2
2006-12-13 03:13:37.058    3
2006-12-13 03:22:08.888    6
2006-12-13 03:31:03.108    1
2006-12-13 03:39:34.937    1
2006-12-13 03:48:07.081    1
2006-12-13 03:56:38.911    2
2006-12-13 04:05:04.117    3

最终结果应该是这样的：

index                      value    new_value
2006-12-05 08:03:01.985    6        
2006-12-05 08:11:34.130    7        
2006-12-05 08:20:05.959    6        
2006-12-05 08:28:38.104    6
2006-12-05 08:37:02.995    6
2006-12-05 08:45:35.140    5
2006-12-05 08:54:06.969    6
2006-12-05 09:02:59.928    6
2006-12-05 09:11:32.072    6
2006-12-05 09:20:03.901    6
2006-12-05 09:28:36.046    5
2006-12-05 09:37:00.937    5
2006-12-05 09:45:33.082    6
2006-12-05 09:54:04.911    6
2006-12-05 10:02:04.889    6
2006-12-05 10:10:37.034    5
2006-12-05 10:19:08.863    6
2006-12-05 10:27:41.008    5        
2006-12-05 10:36:04.953    5            HIGH
2006-12-05 10:44:37.098    5
.
.
.
2006-12-13 02:06:00.898    1
2006-12-13 02:14:33.043    1
2006-12-13 02:23:04.872    1
2006-12-13 02:31:03.904    1
2006-12-13 02:39:36.048    1            LOW
2006-12-13 02:48:07.878    2
2006-12-13 02:56:40.022    5
2006-12-13 03:05:04.914    2
2006-12-13 03:13:37.058    3
2006-12-13 03:22:08.888    6
2006-12-13 03:31:03.108    1
2006-12-13 03:39:34.937    1
2006-12-13 03:48:07.081    1
2006-12-13 03:56:38.911    2
2006-12-13 04:05:04.117    3

我试过这个：

def getNearestDate(items, pivot):
    return min(items, key=lambda x: abs(x - pivot))

items = second_df.index
for pivot in first_df.date:
    d = getNearestDate(items, pivot)
    print(d)
    second_df.loc[second_df.index == d, 'new_value'] = first_df.importance

它打印最近的日期：

2006-12-05 10:36:04.953000
2006-12-13 02:39:36.048000

所以在这些日子里，它应该把价值观放在“重要性”上。此外，new_value列上的所有内容都是 NAN。

你能帮我解决这个问题吗？

标签： pythonpandasdataframetime-seriesassign

解决方案

只需进行这些小改动，希望它会起作用

loc=[]

    def getNearestDate(items, pivot):
        return min(items, key=lambda x: abs(x - pivot))
    
    items = second_df.index
    for pivot in first_df.date:
        d = getNearestDate(items, pivot)
        loc.append(second_df.set_index('index').index.get_loc(d))
    
    ## Adding Data to your second df   
    second_df['importance']=[]
    for index,locations in enumerate(loc):
        df['importance'][int(location)]=first_df['importance'][index]

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