我的代码缺少一些我试图退出文件的行

Question

The basic task is to write a function, get_words_from_file(filename), that returns a list of lower case words that are within the region of interest. They share with you a regular expression: "[az]+[-'][az]+|[az]+[']?|[az]+", that finds all words that meet this definition. My code works well on some of the tests but fails when the line that indicates the region of interest is repeated. Here's is my code:

import re

def get_words_from_file(filename):
    """Returns a list of lower case words that are with the region of 
    interest, every word in the text file, but, not any of the punctuation."""
    with open(filename,'r', encoding='utf-8') as file:
        flag = False
        words = []
        count = 0
        for line in file:
            if line.startswith("*** START OF"):
                while count < 1:
                    flag=True
                    count += 1
            elif line.startswith("*** END"):
                flag=False
                break       
            elif(flag):
                new_line = line.lower()
                words_on_line = re.findall("[a-z]+[-'][a-z]+|[a-z]+[']?|[a-z]+", 
                                           new_line)
                words.extend(words_on_line)
    
        return words

#test code:
filename = "bee.txt"
words = get_words_from_file(filename)
print(filename, "loaded ok.")
print("{} valid words found.".format(len(words)))
print("Valid word list:")
for word in words:
    print(word)

The issue is the string "*** START OF" is repeated and isn't included when it is inside the region of interest.

The test code should result in:
bee.txt loaded ok.↩
16 valid words found.↩
Valid word list:↩
yes↩
really↩
this↩
time↩
start↩
of↩
synthetic↩
test↩
case↩
end↩
synthetic↩
test↩
case↩
i'm↩
in↩
too

But I'm getting:

bee.txt loaded ok.↩
11 valid words found.↩
Valid word list:↩
yes↩
really↩
this↩
time↩
end↩
synthetic↩
test↩
case↩
i'm↩
in↩
too

Any help would be great! Attached is a screenshot of the file

Answer 1

The specific problem of your code is the if .. elif .. elif statement, you're ignoring all lines that look like the line that signals the start or end of a block, even if it's in the test block.

You wanted something like this for your function:

def get_words_from_file(filename):
    """Returns a list of lower case words that are with the region of
    interest, every word in the text file, but, not any of the punctuation."""
    with open(filename, 'r', encoding='utf-8') as file:
        in_block = False
        words = []
        for line in file:
            if not in_block and line == "*** START OF A SYNTHETIC TEST CASE ***\n":
                in_block = True
            elif in_block and line == "*** END TEST CASE ***\n":
                break
            elif in_block:
                words_on_line = re.findall("[a-z]+[-'][a-z]+|[a-z]+[']?|[a-z]+", line.lower())
                words.extend(words_on_line)

        return words

This is assuming you are actually looking for the whole line as a marker, but of course you can still use .startswith() if you actually accept that as the start or end of the block, as long as it's sufficiently unambiguous.

Your idea of using a flag is fine, although naming a flag to whatever it represents is always a good idea.