添加两个 pandas 数据框 [英] Adding two pandas dataframes

问题描述

我有两个dataframes，都由timeseries索引.我需要将元素加在一起以形成新的dataframe，但前提是索引和列相同.如果该项目不存在于dataframe之一中，则应将其视为零.

I have two dataframes, both indexed by timeseries. I need to add the elements together to form a new dataframe, but only if the index and column are the same. If the item does not exist in one of the dataframes then it should be treated as a zero.

我尝试使用.add，但是无论索引和列如何，这总和.还尝试了一个简单的combined_data = dataframe1 + dataframe2，但是如果两个数据帧都没有该元素，则会给出一个NaN.

I've tried using .add but this sums regardless of index and column. Also tried a simple combined_data = dataframe1 + dataframe2 but this give a NaN if both dataframes don't have the element.

有什么建议吗?

推荐答案

x.add(y, fill_value=0)怎么样?

import pandas as pd

df1 = pd.DataFrame([(1,2),(3,4),(5,6)], columns=['a','b'])
Out: 
   a  b
0  1  2
1  3  4
2  5  6

df2 = pd.DataFrame([(100,200),(300,400),(500,600)], columns=['a','b'])
Out: 
     a    b
0  100  200
1  300  400
2  500  600

df_add = df1.add(df2, fill_value=0)
Out: 
     a    b
0  101  202
1  303  404
2  505  606

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