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That vaguely touches (warning going off topic here, my apologies) my main problem with python. dict.keys() returns an iterator, this is all fine and good, very

That vaguely touches (warning going off topic here, my apologies) my main problem with python. dict.keys() returns an iterator, this is all fine and good, very efficient I suppose, however, the only reason I ever use dict.keys() is so I can sort the keys and you can't sort an iterator so every single dict.keys() in my code base is in the form list(dict.keys()). And it is not even like you need the iterator. A dict works perfectly fine as a key iterator on it's own. /rant

orf 7y ago
> sorted(my_dict.keys()) Or just: > sorted(my_dict) Sorting keys like that is also weird. Keys are insertion ordered, utilize that property where you can and avoid needlessly re-sorting.
- somacert 7y ago
  Glorious, Thank you kind soul for listening to my slightly raving rant. Now I feel several sorts of ashamed at missing what is kind of a core function. salutes
  - hansvm 7y ago
    Fwiw, make sure you're using a newish python version. They weren't always sorted by default.
    - ledauphin 7y ago
      3.6+
marcosdumay 7y ago
> he only reason I ever use dict.keys() is so I can sort the keys Hum... I use dict.keys() every time I use dictionaries to describe some unspecified data set, what happens way more frequently than any use case that requires sorting the keys. It's even incentivized by the language with that kwargs construct and a mainstream usage within libraries. I do agree that the result of dict.keys() should have a sort method. There is no reason not to, but from there it doesn't follow that that making it an iterator is a minor gain. That's the same situation as the GP asking for the removal of a main feature of the library just because he doesn't work with a kind of software that uses it. Congratulations, remove cursors from the library and suddenly Python is a lot less useful for data science.
- orf 7y ago
  It doesn’t and shouldn’t have a sort method because python prefers functions that act on objects rather than methods attached to objects. That’s why you use “len(obj)” rather than “obj.len()”, and why you use “sorted(dict_keys)” rather than adding a “sort” method to random iterables.
  - marcosdumay 7y ago
    Oh, ok. I was comparing it with 'list.sort()', but yeah, this one mutates the list and returns None (just checked it), so 'sorted' is the expected way to sort a dictionary keys, and my post is just wrong.
    - orf 7y ago
      'list.sort()' is one of those leftovers from "Python before it was really Python" and is not one that's particularly worth it to change because it's useful sometimes. In general Python prefers builtins that operate on protocols. You use "len(x)" because it's consistent, otherwise you might call "x.len()", "x.length", "x.size()" or any other number of possibilities. And if an object doesn't define it? You're out of luck. With this any object that supports the protocol (__len__) can be passed to length. The same applies to "sorted()". list.sort() is useful in some specific circumstances where "sorted()" is not adequate, but in general the answer to "how do I sort something" is to use sorted.

orf 7y ago

> sorted(my_dict.keys()) Or just: > sorted(my_dict) Sorting keys like that is also weird. Keys are insertion ordered, utilize that property where you can and avoid needlessly re-sorting.

somacert 7y ago
Glorious, Thank you kind soul for listening to my slightly raving rant. Now I feel several sorts of ashamed at missing what is kind of a core function. salutes
- hansvm 7y ago
  Fwiw, make sure you're using a newish python version. They weren't always sorted by default.
  - ledauphin 7y ago
    3.6+

marcosdumay 7y ago

> he only reason I ever use dict.keys() is so I can sort the keys Hum... I use dict.keys() every time I use dictionaries to describe some unspecified data set, what happens way more frequently than any use case that requires sorting the keys. It's even incentivized by the language with that kwargs construct and a mainstream usage within libraries. I do agree that the result of dict.keys() should have a sort method. There is no reason not to, but from there it doesn't follow that that making it an iterator is a minor gain. That's the same situation as the GP asking for the removal of a main feature of the library just because he doesn't work with a kind of software that uses it. Congratulations, remove cursors from the library and suddenly Python is a lot less useful for data science.

orf 7y ago
It doesn’t and shouldn’t have a sort method because python prefers functions that act on objects rather than methods attached to objects. That’s why you use “len(obj)” rather than “obj.len()”, and why you use “sorted(dict_keys)” rather than adding a “sort” method to random iterables.
- marcosdumay 7y ago
  Oh, ok. I was comparing it with 'list.sort()', but yeah, this one mutates the list and returns None (just checked it), so 'sorted' is the expected way to sort a dictionary keys, and my post is just wrong.
  - orf 7y ago
    'list.sort()' is one of those leftovers from "Python before it was really Python" and is not one that's particularly worth it to change because it's useful sometimes. In general Python prefers builtins that operate on protocols. You use "len(x)" because it's consistent, otherwise you might call "x.len()", "x.length", "x.size()" or any other number of possibilities. And if an object doesn't define it? You're out of luck. With this any object that supports the protocol (__len__) can be passed to length. The same applies to "sorted()". list.sort() is useful in some specific circumstances where "sorted()" is not adequate, but in general the answer to "how do I sort something" is to use sorted.