Python script to filter names and documents

main.py

#!/usr/bin/env python

import csv
import re

def extract_document(names_document):
    return [int(s) for s in names_document.split() if s.isdigit()]

def extract_letters(names_document):
    return " ".join(re.findall(r"(?i)\b[a-z]+\b", names_document))

def invert_last_name(names):
    names = names.split(" ")
    if len(names)>=4:
        return names[2] + " " + names[3] + " " + names[0] + " " + names[1]
    if len(names)==3:
        return names[1] + " " + names[2] + " " + names[0]
    if len(names)==2:
        return names[1] + " " + names[0]
    return names

def main():
    results = []
    with open('Docker_Lima_Meetup_26_de_Octubre.xls', newline='') as csvfile:
        spamreader = csv.reader(csvfile, delimiter=',', quotechar='|')
        x = 0
        for row in spamreader:
            x = x + 1
            if x==1:
                continue

            names = row[0]
            name_2 = extract_letters(row[9])
            if len(name_2)>0:
                names = name_2

            document = extract_document(row[9])
            document_2 = extract_document(row[10])
            if len(document_2)>0:
                document = document_2
            results.append([invert_last_name(names), document])

    with open('results.csv', 'w', newline='') as csvfile:
        spamwriter = csv.writer(csvfile, delimiter=',',
                                quotechar='|', quoting=csv.QUOTE_MINIMAL)
        for row in results:
            spamwriter.writerow(row)


if __name__=="__main__":
    main()