Appending a list of dataframes to a list of dataframe in python

Question

I was hoping to discover an easy solution but I have not been able to come across one. Lets say I have a two lists of 4 dataframes each. Each item of the list is a dataframe. One list is called

list_of_df1

the other is called

list_of_df2

I am wondering if there is away to append the dataframes from one list into the other list. The end goal is to have one combined list with all 8 dataframes. I am sorry I did not provided sample data. I am hoping it is an easy line of code.

This is what I tried:

list_of_df1.append(list_of_df2)
list_of_df1.insert(list_of_df2)

Thank you!

lmiguelvargasf · Accepted Answer · 2019-04-17 17:16:05Z

5

Considering list_of_df1 and list_of_df2 are lists:

list_of_df1.extend(list_of_df2)

edited Apr 17, 2019 at 17:16

answered Apr 17, 2019 at 17:02

lmiguelvargasf

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1 Comment

Jake Over a year ago

Thank you! This code works but I will be using the solution with just adding the two lists together.

BetaDev · Accepted Answer · 2019-04-17 17:11:06Z

4

Try pd.concat(frames)

import pandas as pd

d1 = {'ID': [10,20,40,50], 'Name': ["Bob", "John","test","Foo"]}   
d2 = {'ID': [10,20,40,50], 'Name': ["Bob", "John","test","Foo"]}   
df1 = pd.DataFrame(data=d1)
df2 = pd.DataFrame(data=d2)

frames = [df1, df2]
result = pd.concat(frames)
print(result)

Output:

ID  Name
 10   Bob
 20  John
 40  test
 50   Foo
 10   Bob
 20  John
 40  test
 50   Foo

If you have list of DFs, then the solution posted by @ruohola is the one that you are looking for.

edited Apr 17, 2019 at 17:11

answered Apr 17, 2019 at 17:03

BetaDev

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3 Comments

lmiguelvargasf Over a year ago

I think this will be valid if he wants one dataframe that has the contents of all the dataframes in the list, but he is saying that he wants a list of all dataframes.

BetaDev Over a year ago

Okay let me update the answer. THanks. I thought he is saying list means list of data inside a dataframe.

ruohola Over a year ago

This doesn't do what the OP asks.

ruohola · Accepted Answer · 2019-04-17 17:03:03Z

3

As simple as:

list_of_df1 += list_of_df2

This is actually extremely slightly more efficient than using extend(), since it doesn't include the overhead of a function call.

answered Apr 17, 2019 at 17:03

ruohola

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2 Comments

Jake Over a year ago

Thank you! This is exactly the easy solution I was looking for!

ruohola Over a year ago

@Jake Glad I could help! :)

Suraj Rao · Accepted Answer · 2021-12-10 11:18:17Z

1

The starred expression remove the brackets of the list.

[*list_df1, *list_df2]

Probably not the most efficient though.

edited Dec 10, 2021 at 11:18

Suraj Rao

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answered Dec 10, 2021 at 11:12

Tegh

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