Python: extracting text from strings using a key phrase

Question

Struggling trying to find a way to do this, any help would be great.

I have a long string – it’s the Title field. Here are some samples.

AIR-LAP1142N-A-K
AIR-LP142N-A-K
Used Airo 802.11n Draft 2.0 SingleAccess Point AIR-LP142N-A-9
Airo AIR-AP142N-A-K9 IOS Ver 15.2
MINT Lot of (2) AIR-LA112N-A-K9 - Dual-band-based 802.11a/g/n
Genuine Airo 112N  AP AIR-LP114N-A-K9 PoE
Wireless AP AIR-LP114N-A-9  Airy 50 availiable

I need to pull the part number out of the Title and assign it to a variable named ‘PartNumber’. The part number will always start with the characters ‘AIR-‘.

So for example-

Title = ‘AIR-LAP1142N-A-K9 W/POWER CORD’
PartNumber = yourformula(Title)

Print (PartNumber) will output AIR-LAP1142N-A-K9

I am fairly new to python and would greatly appreciate help. I would like it to ONLY print the part number not all the other text before or after.

Answer 1

What you’re looking for is called regular expressions and is implemented in the re module. For instance, you’d need to write something like :

>>> import re
>>> def format_title(title):
...     return re.search("(AIR-\S*)", title).group(1)
>>> Title = "Cisco AIR-LAP1142N-A-K9 W/POWER CORD"
>>> PartNumber = format_title(Title)
>>> print(PartNumber)
AIR-LAP1142N-A-K9

The \S ensures you match everything from AIR- to the next blank character.

Answer 2

def yourFunction(title):
    for word in title.split():
        if word.startswith('AIR-'):
            return word

>>> PartNumber = yourFunction(Title)
>>> print PartNumber

AIR-LAP1142N-A-K9

Answer 3

This is a sensible time to use a regular expression. It looks like the part number consists of upper-case letters, hyphens, and numbers, so this should work:

import re
def extract_part_number(title):
    return re.search(r'(AIR-[A-Z0-9\-]+)', title).groups()[0]

This will throw an error if it gets a string that doesn't contain something that looks like a part number, so you'll probably want to add some checks to make sure re.search doesn't return None and groups doesn't return an empty tuple.

Answer 4

You may/could use the .split() function. What this does is that it'll split parts of the text separated by spaces into a list.

To do this the way you want it, I'd make a new variable (named whatever); though for this example, let's go with titleSplitList. (Where as this variable is equal to titleSplitList = Title.split())

From here, you know that the part of text you're trying to retrieve is the second item of the titleSplitList, so you could assign it to a new variable by:

PartNumber = titleSplitList[1]

Hope this helps.