Import multiple csv files into pandas and concatenate into one DataFrame

Question

I would like to read several csv files from a directory into pandas and concatenate them into one big DataFrame. I have not been able to figure it out though. Here is what I

Answer 1

Almost all of the answers here are either unnecessarily complex (glob pattern matching) or rely on additional 3rd party libraries. You can do this in 2 lines using everything Pandas and python (all versions) already have built in.

For a few files - 1 liner:

df = pd.concat(map(pd.read_csv, ['data/d1.csv', 'data/d2.csv','data/d3.csv']))

For many files:

from os import listdir

filepaths = [f for f in listdir("./data") if f.endswith('.csv')]
df = pd.concat(map(pd.read_csv, filepaths))

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This pandas line which sets the df utilizes 3 things:

1. Python's map (function, iterable) sends to the function (the pd.read_csv()) the iterable (our list) which is every csv element in filepaths).
2. Panda's read_csv() function reads in each CSV file as normal.
3. Panda's concat() brings all these under one df variable.