Python: Error:TypeError: findall() missing 1 required positional argument: 'string'

问题

I am trying to scrub a text document with specific parameters. Have tried different iterations of the x=... line but the program isn't able to read the all line.

import re
#import csv

text = open(r'C:\Users\Vincent\Documents\python\theSortingHat\100000DirtyNames.txt') #open text file
for line in text: #iterate through every line
    #return list of names in that line
    x = re.findall ('^([a-zA-Z]-?$')
    #if an actual name is found
    if x != 0:
        print(x)

I receive:

Error:TypeError: findall() missing 1 required positional argument: 'string'

回答1:

You need to find something in a string. The problem is that you gave re.findall only the one parameter, you should also give line as a parameter. You also had some problem with your regex and you didn't close your group (i.e. ()), what made it to a not valid regex.

This is the answer that you are aiming for:

import re

text = open(r'C:\Users\Vincent\Documents\python\theSortingHat\100000DirtyNames.txt') #open text file
for line in text: #iterate through every line
    #return list of names in that line
    x = re.findall('^([a-zA-Z])-?$', line)
    #if an actual name is found
    if x != 0:
        print(x)

---

About the regex, sounds like this post might help
TL;DR:
you can use this regex maybe:

^[A-Z]'?[- a-zA-Z]+$

来源：https://stackoverflow.com/questions/54496411/python-errortypeerror-findall-missing-1-required-positional-argument-stri