Regex to dynamically find pattern - Python

Question

I have a Python list which looks like below, I would like to build a regex to validate if my input strings match the list format.

list = ['The Computer name is *** and its RAM is ***','The Laptop is from *** Brand','The Laptop has windows ***/']

So the Python list has a collection of Strings, along with the following special set of characters: * = Match one word */ = Match one or more words

rest of the words in the list should be an exact match.

So basically I need to loop through the list, and compare it with an input String to see if my input string matches the format in the list.

For eg: I need to compare string a to list item 0, the string would be "The Computer name is Dell and its RAM is 2gb" this string would pass the validation. Whereas the following string would fail the validation "The Computer name is Dell and its RAM is 2 gb" because "2 gb" is 2 words and in our validation list we are expecting one word.

Why not use regular expressions as patterns, especially since you already tagged them? — DYZ
– DYZ, Commented Apr 5, 2020 at 8:07
How do I create this dynamically? since the list contains multiple patterns — asmij kun
– asmij kun, Commented Apr 5, 2020 at 8:16
You either must have a closed set of patterns or a rule to generate them. — DYZ
– DYZ, Commented Apr 5, 2020 at 8:21
I understood Binh's logic and accepted his answer, however he went too strict with the data and matched exactly what I wanted , so if I try to name my pc "asm-1.2" the validation fails because he is only matching [a-zA-Z] , I tried \w and didnt get a match as well. How can I match any word with special characters as well? — asmij kun
– asmij kun, Commented Apr 5, 2020 at 8:39

Binh · Accepted Answer · 2020-04-05 08:19:25Z

1

So your list should be:

list = ['The Computer name is [a-zA-Z]+? and its RAM is \d+[gbGB]+', 'The Laptop is from [a-zA-Z]+? Brand', 'The Laptop has windows [a-zA-Z ]+?']
text = input('type someting: ')
for item in list:
    if re.match(f'{item}', text):
        #do something

answered Apr 5, 2020 at 8:19

Binh

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6 Comments

asmij kun Over a year ago

oh, so your suggesting me to replace the *** with the regex expressions, I understand, thanks a lot

asmij kun Over a year ago

what does the 'f' do in re.match?

Binh Over a year ago

the f allows you to put a variable inside a string. Ex: x=5 and you can print(f'your value is {x}') ==> your value is 5. In the answer above, {item} is a string in list, ex: item = 'The Computer name is [a-zA-Z]+? and its RAM is \d+[gbGB]+' at 1st iteration in for loop

Binh Over a year ago

@asmijkun docs.python.org/3/whatsnew/3.6.html#whatsnew36-pep498

Binh Over a year ago

[^ ] will match anything except space

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