在 python 中使用带有正则表达式的多个变量

Question

I'm trying to search strings with variable using Regular expression operations.
I browsed about it and find this useful code

s = "These are oranges and apples and pears, but not pinapples or .."
r = re.compile(r'\bAND\b | \bOR\b | \bNOT\b', flags=re.I | re.X)
r.findall(s)

['and', 'and', 'not', 'or'] #result

In this code they using exact string value 'AND''OR''NOT'.
What should i do if i have something like this,

a = 'AND'
b = 'OR'

(I'm getting these string values by running a loop)
In this code they are using '| (or)' and re.findall() , what should i do if i need to search both a and b. and use re.search()

Note: I think i need to use r'\bfoo\b' because sometimes my matches will be in this way... 'foo.', '(foo)''cod.foo'
because of this i can't use condition like if a in s: (or) if a and b in s: .
Please give some suggestions to work on this, Thank you.

Answer 1

I might not know what you are going to do, but if your intention is to use variables inside regex, then remember that a regex, before it is send to re.compile , is just a simple text. So you can do with it everything you can do with texts like:

re.compile(f"\\b({a}|{b})\\b")

or in older python:

re.compile("\\b(" + a + "|" + b + ")\\b")

You are not restricted to use r"text" to define regex patterns.

Answer 2

If you want to search both variables, you can call re.search twice
Something like this...

if((re.search(rf"\b(?=\w){(a)}\b(?!\w)", s, re.IGNORECASE)) and (re.search(rf"\b(?=\w){(b)}\b(?!\w)", s, re.IGNORECASE))): 

Hope it helps

Answer 3

I think you need something like this, and add flag "case insensitive" too:

pattern = '\b(and|or|not)\b'