How to import multiple csv files and concatenate into one DataFrame using pandas

user_14877231 0
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I have problem No objects to concatenate. I can not import .csv files from main and its subdirectories to concatenate them into one DataFrame. I am using pandas. Old answers did not help me so please do not mark as duplicated.

Folder structure is like that

main/*.csv
main/name1/name1/*.csv
main/name1/name2/*.csv
main/name2/name1/*.csv
main/name3/*.csv

import pandas as pd
import os
import glob

folder_selected = 'C:/Users/jacob/Documents/csv_files'
  1. not works
frame = pd.concat(map(pd.read_csv, glob.iglob(os.path.join(folder_selected, "/*.csv"))))
  1. not works
csv_paths = glob.glob('*.csv')
dfs = [pd.read_csv(folder_selected) for folder_selected in csv_paths]
df = pd.concat(dfs)
  1. not works
            all_files = []
            
            all_files = glob.glob (folder_selected + "/*.csv")
            
            file_path = []
            for file in all_files:
                df = pd.read_csv(file, index_col=None, header=0)
                file_path.append(df)
                    
        frame = pd.concat(file_path, axis=0, ignore_index=False)
pandas dataframe csv python
3 Answers

You need to search the subdirectories recursively.

folder = 'C:/Users/jacob/Documents/csv_files'
path = folder+"/**/*.csv"
  1. Using glob.iglob
df = pd.concat(map(pd.read_csv, glob.iglob(path, recursive=True)))
  1. Using glob.glob
csv_paths = glob.glob(path, recursive=True)
dfs = [pd.read_csv(csv_path) for csv_path in csv_paths]
df = pd.concat(dfs)
  1. Using os.walk
file_paths = []
for base, dirs, files in os.walk(folder):
    for file in fnmatch.filter(files, '*.csv'):
        file_paths.append(os.path.join(base, file))
df = pd.concat([pd.read_csv(file) for file in file_paths])
  1. Using pathlib
from pathlib import Path
files = Path(folder).rglob('*.csv')
df = pd.concat(map(pd.read_csv, files))
user_120115890
user_140491840

Python’s pathlib is a tool for such tasks

from pathlib import Path

FOLDER_SELECTED = 'C:/Users/jacob/Documents/csv_files'

path = Path(FOLDER_SELECTED) / Path("main")

# grab all csvs in main and subfolders
df = pd.concat(pd.read_csv(f.name) for f in path.rglob("*.csv"))

Note:

If the CSV need preprocing, you can create a read_csv function to deal with issues and place it in place of pd.read_csv

user_68582440
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