检查多个正则表达式模式

Question

I am working on a calculator for feet and inch calculations. I currently have a program that works but so far I can only get it to work if you input the full measurement (ie 4'-0" instead of just 4' or 0'-6" instead of just 6"). I would like to be able to have it check against a few patterns as to be able to input just feet, inches, fractions of an inch, or a combination of the above.

I have tried making one variable with all the different patterns in it but I must be missing something to be able to parse through the variable to find the correct pattern (this attempted is commented out in the code). I found other code using this method and tried to replicate it to work for me but no luck. I have also tried making each pattern its own variable but then I was unsure how to check against each pattern and return whether or not it was a match. Maybe I am over thinking this and its easy but I am stumped.

Sorry for posting a link to the entire code but I figured that it was easier for you to be able to see and use what I am working with instead of just code snippets. Thanks in advance for any help.

Link to the code:

https://repl.it/repls/PrestigiousKeyMemorypool

Answer 1

Try using named groups and make each part optional (including the dash):

regex = re.compile(r'(?P<feet>[0-9]+\')?\-?(?P<inches>[0-9]+")?')

And modify the following functions and you will be set.

def ftbreakdown(*args):
  search = regex.search(*args)
  print(search)
  feetsearch = search.group('feet')
  feet = int(feetsearch.split("'")[0]) if feetsearch is not None else 0
  return feet

def inbreakdown(*args):
  search = regex.search(*args)
  print(search)
  if search is None:
    inches = 0
  else:
    inchsearch = search.group('inches')
    inches = int(inchsearch.split('"')[0]) if inchsearch is not None else 0
  # print(inches)
  return inches

This is the quick and dirty way, but it works. You can obviously poptimize this further.

Sample run

Python 3.6.1 (default, Dec 2015, 13:05:11)
[GCC 4.8.2] on linux
Enter length: 4'-2"
Choose operation: +
Enter length: 6"
<_sre.SRE_Match object; span=(0, 5), match='4\'-2"'>
<_sre.SRE_Match object; span=(0, 2), match='6"'>
<_sre.SRE_Match object; span=(0, 5), match='4\'-2"'>
<_sre.SRE_Match object; span=(0, 2), match='6"'>
4'-8"
Choose operation: