Reading filenames from the directory

Question

I want to get two separate lists of file names using glob, with each list having the same type of files. I have two type of data files. For example,

1. 2018-01-02.dat
2. 2018-01-02_patients.dat

The only difference is that the second file type is followed by "_patients". A date can be anything but the format is consistent. How can I accomplish this using glob?

Answer 1

To precisely match the digits, you can use the glob patterns:

[0-9][0-9][0-9][0-9]-[0-9][0-9]-[0-9][0-9].dat  # matches e.g. 2018-01-02.dat
[0-9][0-9][0-9][0-9]-[0-9][0-9]-[0-9][0-9]_patients.dat  # matches e.g. 2018-01-02_patients.dat

You can also use the ? instead of [0-9] to match any single character, if you are sure about the absence of any other alike patterns.

In [103]: glob.glob('[0-9][0-9][0-9][0-9]-[0-9][0-9]-[0-9][0-9].dat')
Out[103]: ['2018-01-02.dat', '2014-03-12.dat']

In [104]: glob.glob('[0-9][0-9][0-9][0-9]-[0-9][0-9]-[0-9][0-9]_patients.dat')
Out[104]: ['2018-01-02_patients.dat', '2014-03-12_patients.dat']

Answer 2

You can use re with glob:

import glob
import re
final_files = [i for i in glob.glob('*') if re.findall('\.dat$|_patients\.dat$', i)]