pandas Pandas IO tools (reading and saving data sets) List comprehension


Example

All files are in folder files. First create list of DataFrames and then concat them:

import pandas as pd
import glob

#a.csv
#a,b
#1,2
#5,8

#b.csv
#a,b
#9,6
#6,4

#c.csv
#a,b
#4,3
#7,0

files = glob.glob('files/*.csv')
dfs = [pd.read_csv(fp) for fp in files]
#duplicated index inherited from each Dataframe
df = pd.concat(dfs)
print (df)
   a  b
0  1  2
1  5  8
0  9  6
1  6  4
0  4  3
1  7  0
#'reseting' index
df = pd.concat(dfs, ignore_index=True)
print (df)
   a  b
0  1  2
1  5  8
2  9  6
3  6  4
4  4  3
5  7  0
#concat by columns
df1 = pd.concat(dfs, axis=1)
print (df1)
   a  b  a  b  a  b
0  1  2  9  6  4  3
1  5  8  6  4  7  0
#reset column names
df1 = pd.concat(dfs, axis=1, ignore_index=True)
print (df1)
   0  1  2  3  4  5
0  1  2  9  6  4  3
1  5  8  6  4  7  0