Python regex statement errors

Question

I am new to using regex and would really appreciate any help here. I have to parse a file with strings of following formats (main difference being that the second string has an extra "-" string in the middle:

Abc_p123 abc_ghi_data

OR
Abc_de*_p123 abc_ghi_data

I could write a regex to match the first and second strings separately:

data_lst = re.findall('([a-zA-Z0-9]+_p\d{3})\s.*_data.*', content, re.IGNORECASE)
data_lst = re.findall('([a-zA-Z0-9]+_[a-zA-Z]+_p\d{3})\s.*_data.*', content, re.IGNORECASE)

Can someone guide on how to combine the two findall regex, so that it works with both strings. I can still create a combined single list by appending the second findall statement to first list. However, I am sure there is a way to handle it in one findall regex statement. I tried ".*" in the middle but, that gives error.

Please advise. Thanks,

Yes, in some cases we have it and in other cases we don't (then it is same as string1) — Aisha
– Aisha, Commented Nov 2, 2020 at 20:36

MonkeyZeus · Accepted Answer · 2020-11-02 20:37:52Z

2

You were very close:

([a-zA-Z0-9]+(?:_[a-zA-Z]+\*)?_p\d{3})\s.*_data.*

Here is the important part:

(?:_[a-zA-Z]+\*)?

It says: optionally match an underscore, followed by unlimited a-z, followed by a asterisk.

https://regex101.com/r/5XCsPK/1

answered Nov 2, 2020 at 20:37

MonkeyZeus

20.8k4 gold badges41 silver badges83 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Vincent · Accepted Answer · 2020-11-02 20:38:09Z

1

You could try

([a-zA-Z0-9]+(_[a-zA-Z]+)?_p\d{3})\s.*_data.*

I replaced _[a-zA-Z]+ with (_[a-zA-Z]+)? to make it optional.

And if you don't want the extra capture group, add ?: like so: (?:_[a-zA-Z]+)?

Demo: https://regex101.com/r/5xynlx/2

answered Nov 2, 2020 at 20:38

Vincent

5,0433 gold badges21 silver badges30 bronze badges

3 Comments

The fourth bird Over a year ago

The pattern misses the * in Abc_de*_p123 abc_ghi_data

Vincent Over a year ago

Nope, OP said he matches successfully the second string using ([a-zA-Z0-9]+_[a-zA-Z]+_p\d{3})\s.*_data.* so I think * meant 'any random list of letters', (which I agree was misleading, but if he really wanted to match the star, then he wouldn't say ([a-zA-Z0-9]+_[a-zA-Z]+_p\d{3})\s.*_data.* is working)

The fourth bird Over a year ago

Ok, I see what you mean. In that case it is misleading.

Ryszard Czech · Accepted Answer · 2020-11-02 20:37:11Z

Use

([a-zA-Z0-9]+(?:_[a-zA-Z0-9*]+)?_p\d{3})\s.*_data

See proof

Explanation

--------------------------------------------------------------------------------
  (                        group and capture to \1:
--------------------------------------------------------------------------------
    [a-zA-Z0-9]+             any character of: 'a' to 'z', 'A' to
                             'Z', '0' to '9' (1 or more times
                             (matching the most amount possible))
--------------------------------------------------------------------------------
    (?:                      group, but do not capture (optional
                             (matching the most amount possible)):
--------------------------------------------------------------------------------
      _                        '_'
--------------------------------------------------------------------------------
      [a-zA-Z0-9*]+            any character of: 'a' to 'z', 'A' to
                               'Z', '0' to '9', '*' (1 or more times
                               (matching the most amount possible))
--------------------------------------------------------------------------------
    )?                       end of grouping
--------------------------------------------------------------------------------
    _p                       '_p'
--------------------------------------------------------------------------------
    \d{3}                    digits (0-9) (3 times)
--------------------------------------------------------------------------------
  )                        end of \1
--------------------------------------------------------------------------------
  \s                       whitespace (\n, \r, \t, \f, and " ")
--------------------------------------------------------------------------------
  .*                       any character except \n (0 or more times
                           (matching the most amount possible))
--------------------------------------------------------------------------------
  _data                    '_data'

Collectives™ on Stack Overflow

Python regex statement errors

3 Answers 3

Comments

3 Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

Comments

3 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related