Loading multiple csv files of a folder into one dataframe

I suggest use list comprehension with concat:

import glob
import pandas as pd

files = glob.glob("TransactionData\Promorelevant*.csv")
dfs = [pd.read_csv(f, header=None, sep=";") for f in files]

salesdata = pd.concat(dfs,ignore_index=True)

With a help from link to actual answer

This seems to be the best one liner:

import glob, os    
df = pd.concat(map(pd.read_csv, glob.glob(os.path.join('', "*.csv"))))