pandas iterate over many dataframe and create list of occurance per key

Question

I have the few hundreds of dataframe with the same sturcture.
I want to aggregate per key as follows:
For the list columns – create a list of lists (where each list is the value of specific dataframe)
For example in case of 2 datarames:

df1 =  
Key  C1.  C2. C3
 A  [1,2]  6   b
 B  [6,1]  9   c

df2 = 
Key  C1   C2   C3
 B  [5,8]  2    t
 A  [7,2]  3    z

df_agg =  
   Key      C1          C2        C3 
    A  [[1,2],[7,2]]   [6,3]    [b,z]  
    B  [[6,1],[5,8]]   [9,2]    [c,t]

Please notice I have few hundreds: df1, df2, … dfn

Asked By: Cranjis

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Source

Answer 1

EDIT: Solution for list of DataFrames – use concat and aggregate list:

dfs = [df1, df2]

df = pd.concat(dfs).groupby('Key', as_index=False).agg(list)
print (df)
  Key                C1      C2      C3
0   A  [[1, 2], [7, 2]]  [6, 3]  [b, z]
1   B  [[6, 1], [5, 8]]  [9, 2]  [c, t]

Answered By: jezrael

pandas iterate over many dataframe and create list of occurance per key

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