I have a for loop that generates different pandas dataframes whose values I want to save sequentially [duplicate]

Question

I made a for loop that creates a different pandas dataframe on each iteration. Something like this -> First iteration:

index	Letter	Value
0	A	1
1	B	2
2	C	3

Second iteration:

index	Letter	Value
0	C	5
1	D	3
2	E	1
3	F	2

Third iteration:

index	Letter	Value
0	A	2
1	F	1

I want to save each dataframe to a new one that looks like this:

index	Letter	Value	Value	Value
0	A	1		2
1	B	2
2	C	3	5
3	D		3
4	E		1
5	F		2	1

Also, new letters can appear on each iteration, so for example if 'G' appears for the first time on interation 'n', a new row would need to be created on the desired consolidated dataframe.

Answer 1

You can make Letter the index for each dataframe, and then use pd.concat with axis=1:

dataframes = [df1, df2, df3]
new_df = pd.concat([d.set_index('Letter') for d in dataframes], axis=1)

Output:

>>> new_df
        Value  Value  Value
Letter                     
A       1.0   NaN     2.0  
B       2.0   NaN    NaN   
C       3.0    5.0   NaN   
D      NaN     3.0   NaN   
E      NaN     1.0   NaN   
F      NaN     2.0    1.0