Question

I want to search a tuple of tuples for a particular string and return the index of the parent tuple. I seem to run into variations of this kind of search frequently.

What is the most pythonic way to do this?

I.E:

derp = (('Cat','Pet'),('Dog','Pet'),('Spock','Vulcan'))
i = None
for index, item in enumerate(derp):
    if item[0] == 'Spock':
         i = index
         break
>>>print i
2

I could generalize this into a small utility function that takes an iterable, an index (I’ve hard coded 0 in the example) and a search value. It does the trick but I’ve got this notion that there’s probably a one-liner for it 😉

I.E:

def pluck(iterable, key, value):
    for index, item in enumerate(iterable):
        if item[key] == value:
             return index
    return None

Answer 1

It does the trick but I’ve got this notion that there’s probably a one-liner for it 😉

The one-liner is probably not the pythonic way to do it 🙂

The method you have used looks fine.

Edit:

If you want to be cute:

return next( (i for i,(k,v) in enumerate(items) if k=='Spock'),None)

next takes a generator expression and returns the next value or the second argument (in this case None) once the generator has been exhausted.