Create a list from searching a text file for [ ]-CodePudding

I'm trying to create a list from a text file that I am reading into Python. The text file contains a bunch of square brackets throughout the file [some text here]. What I am trying to do is first count how many of those square bracket pairings I have [] and then add whatever text is inside of them into a list.

Here is a super simplified version of the text file I am trying to use with the brackets:

"[name] is going to the store! It's going to be at [place] on [day-of-the-week]."

Here is what I have:

bracket_counter = 0

file_name = "example.txt"
readFile = open(file_name)
text_lines = readFile.readlines()

for line in text_lines:
    val = line.split('[', 1)[1].split(']')[0]
    print(val)
    if line has [ and ]:
        bracket_counter  = 1

I'm super new to Python. I don't know if I should be using regular expressions for this or if that is overcomplicating things.

Thanks for your help!

CodePudding user response：

You can of course use regular expressions for that. In the following example, you're extracting all content within square brackets and store them in the variable words.

words = re.findall(r'\[([^\]] )\]', line)

Don't forget to import re at the top of your program.

Explanation of the regex:

\[ and \] match square brackets. As these are used in regex as well, you have to escape them with a backslash
(...) is a capturing group, all regex parts within normal brackets will be returned as a finding (for e.g. in the list words)
[^\]] will match all characters except the ]

To put it all together:

This regex looks for an opening square bracket, then matches all characters until a closing square bracket appears and returns the matches within a list.

CodePudding user response：

Python doesn't have a has keyword. You're probably looking for something like:

('[' in line) or (']' in line)

which will evaluate to True if the line includes [ or ].

CodePudding user response：

If there's a lonely soul out there like me who wondered how this could be done without using regex, I guess this could be a solution also:

results = []
with open("example.txt") as read:
    for line in read:
        start = None; end = None
        for i,v in enumerate(line):
            if v == "[": start = i
            if v == "]": end = i
            if start is not None and end is not None:
                results.append(line[start 1:end])
                start = None; end = None

print(results)

Result:

['name', 'place', 'day-of-the-week']