[Tutor] How to find a word in a string

[Peter Otten]

On 04/05/2021 03:09, Phil wrote:
> This is a bit trickier that I had at first thought, for example:
> 
> test = 'Do this, then do that.'
> 
> if 'this' in test.lower().split():
>      print('found')
> else:
>      print('not found')
> 
> Does not find 'this' because of the comma.
> 
> I had experimented with .find() but that's not the answer either because 
> if I was searching a sentence for 'is' it would be found in 'this' 
> rather than only 'is' as a word. I also thought about striping all 
> punctuation but that seems to be unnecessarily complicated.
> 
> So, how I might I deal with the comma in this case?


If you want to avoid regular expressions you can replace punctuation 
with spaces before splitting.
The obvious way would be

test.replace(".", " ").replace(",", " ").replace(...

but there's also str.translate() to deal with multiple (character) 
replacements simultaneously:

 >>> punct = ",;:.!"
 >>> clean = str.maketrans(punct, " " * len(punct))
 >>> test = "Do this, then do that."
 >>> test.translate(clean)
'Do this  then do that '

 >>> if "this"in test.translate(clean).lower().split():
	print("found")

	
found

There are still problems like the "-" which may or may not be part of a 
word.