How to iterate through a folder of csv files - python-3.x

Question

I'm really new to python, so please bear with me!
I have folder on my desktop that contains a few csv files named as "File 1.csv", "File 2.csv" and so on. In each file, there is a table that looks like:
Animal Level
Cat 1
Dog 2
Bird 3
Snake 4
But each one of the files has a few differences in the "Animal" column. I wrote the following code that compares only two files at a time and returns the animals that match:
def matchlist(file1, file2):
new_df = pd.DataFrame()
file_one = pd.read_csv(file1)
file_two = pd.read_csv(file2)
for i in file_one["Animal"]:
df_temp = file_two[file_two["Animal"] == i]
new_df = new_df.append(df_temp)
df_temp = pd.DataFrame()
return new_df
But that only compares two files at a time. Is there a way that will iterate through all the files in that single folder and return all the ones that match to the new_df above?
For example, new_df compares file 1 and file 2. Then, I am looking for code that compares new_df to file 3, file 4, file 5, and so on.
Thanks!

Answer 1

Im not sure if it is really what you want, i can't comment yet on you questions... so:
this function returns a dataframe with animals that can be found in all csv files (can be very small) it uses the animal name as key, so the level value will not be considered
import pandas as pd
import os, sys
def matchlist_iter(folder_path):
# get list with filenames in folder and throw away all non ncsv
files = [file_path for file_path in os.listdir(folder_path) if file_path.endswith('.csv')]
# init return df with first csv
df = pd.read_csv(os.path.join(folder_path, files[0]), )
for file_path in files[1:]:
print('compare: {}'.format(file_path))
df_other = pd.read_csv(os.path.join(folder_path, file_path))
# only keep the animals that are in both frames
df = df_other[df['Animal'].isin(df_other['Animal'])]
return df
if __name__ == '__main__':
matched = matchlist_iter(sys.argv[1])
print(matched)
i've found a similar question with more answerers regarding the match here: Compare Python Pandas DataFrames for matching rows
EDIT: added csv and sample output
csv
Animal, Level
Cat, 1
Dog, 2
Bird, 3
Snake, 4
csv
Animal, Level
Cat, 1
Parrot, 2
Bird, 3
Horse, 4
output
compare: csv2.csv
Animal Level
0 Cat 1
2 Bird 3

Answer 2

I constructed a set of six files in which only the first columns of File 1.csv and File 6.csv are identical.
You need only the first column of each csv for comparison purposes, I therefore arrange to extract only those from each file.
>>> import pandas as pd
>>> from pathlib import Path
>>> column_1 = pd.read_csv('File 1.csv', sep='\s+')['Animal'].tolist()
>>> column_1
['Cat', 'Dog', 'Bird', 'Snake']
>>> for filename in Path('.').glob('*.csv'):
... if filename.name == 'File 1.csv':
... continue
... next_column = pd.read_csv(filename.name, sep='\s+')['Animal'].tolist()
... if column_1 == next_column:
... print (filename.name)
...
File 6.csv
As expected, File 6.csv is the only file found to be identical (in the first column) to File 1.csv.