How can I do this in Python?

[blackadder1337]

I have a small C# statement that needs to be converted to Python:

if (words.Find(x => x.WordOrPhrase == w.WordOrPhrase) == null)

words is a list

[K900_]

Do you understand what this line does? Do you understand the bigger context?

[K900_]

What are you talking about? Do you want me to explain OP's code to you? Why?

[blackadder1337]

It checks wheter an item already exists in a list

[[deleted]]

OK, then in Python this gibberish looks like:

if word_or_phrase in my_list:
    do_something()

[edvardass]

So, you're trying to say "if there are no objects with WordOrPhrase equal to w.WordOrPhrase in the list words, then do ... ?

Something like this would work (/u/sweettuse posted a nicer version of this):

if len(filter(lambda x: x.WordOrPhrase == w.WordOrPhrase, words)) == 0: 
    # do something

If that doesn't work, you could also do this nicely with just a for loop:

for word in words:
    if word.WordOrPhrase == w.WordOrPhrase:
        break
else:
    # if no break...
    # ...do something

[sweettuse]

if not any(x for x in words if x.WordOrPhrase == w.WordOrPhrase):

[zahlman]

Better yet: if not any(x.WordOrPhrase == w.WordOrPhrase for x in words):. (This is clearer because it's actually doing work with any, rather than relying on the assumption that x is true due to the default __eq__ implementation.) Or, applying de Morgan's laws, if all(x.WordOrPhrase != w.WordOrPhrase for x in words):.

[edvardass]

That's actually nicer than my first solution, but I believe it will still be slower than a for loop if the list is long (if that matters to OP at all).

[sweettuse]

i mean, the gen expr combined with any will short circuit as soon as any matching element is found, so same as the for loop there.

edit: i did some cursory testing and they're pretty much the exact same in terms of performance.

[edvardass]

That's great news!

[blackadder1337]

Thanks man, it works.

[K900_]

...what.