匹配文件名后撤消files.split（python 3.x）

Question

Filenames:

File1: new_data_20100101.csv File2: samples_20100101.csv

timestamp is always = %Y%m%d in the filename after a _ and before .csv

I want to find the files where there is a data and a samples file and then do something with those files: My Code so far:

for all_files in os.listdir():
    if all_files.__contains__("data_"):
        dataList.append(all_files.split('_')[2])
    if all_files.__contains__("samples_"):
        samplesList.append(all_files.split('_')[1])

that gives me the filenames cut down to the Timestamp and the extension .csv

Now I would like to try something like this

for day in dataList:
    if day in sampleList:
         open day as csv.....

I get a list of days where both files have timestamps... how can I undo that files.split now so aI can go on working with the files since now I would get an error telling me that for instance _2010010.csv does not exist because it's new_data_2010010.csv I'm kinda unsure on how to use the os.basename so I would appreciated some advice on the data names. thanks

Answer 1

You could instead use the glob module to get your list. This allows you to filter just your CSV files.

The following script creates two dictionaries with the key for each dictionary being the date portion of your filename and the value holding the whole filename. A list comprehension creates a list of tuples holding each matching pair:

import glob
import os

csv_files = glob.glob('*.csv')

data_files = {file.split('_')[2] : file for file in csv_files if 'data_' in file}
sample_files = {file.split('_')[1] : file for file in csv_files if 'samples_' in file}
matching_pairs = [(sample_files[date], file) for date, file in data_files.items() if date in sample_files]

for sample_file, data_file in sorted(matching_pairs):
    print('{} <-> {}'.format(sample_file, data_file))

For your two file example, this would display the following:

samples_20100101.csv <-> new_data_20100101.csv