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11 Νοε 2013 · It can also be very useful in Python's console to quickly check a class' attributes and methods. Or an object's attributes (I know I just said we can't rely on it, but in the console who cares if it fails sometimes or if it's not accurate).
2 Μαΐ 2013 · I wanted to test if a key exists in a dictionary before updating the value for the key. I wrote the following code: if 'key1' in dict.keys(): print "blah" else: print "boo" I think this is no...
21 Ιουλ 2010 · Why is it 'better' to use my_dict.keys() over iterating directly over the dictionary? Iteration over a dictionary is clearly documented as yielding keys. It appears you had Python 2 in mind when you answered this, because in Python 3 for key in my_dict.keys() will still have the same problem with changing the dictionary size during iteration.
21 Ιουν 2009 · Another efficient way of doing this with the update method is with keyword arguments, but since they have to be legitimate python words, you can't have spaces or special symbols or start the name with a number, but many consider this a more readable way to create keys for a dict, and here we certainly avoid creating an extra unnecessary dict:
You can also use python's collections.ChainMap which was introduced in python 3.3. from collections import ChainMap c = ChainMap(a, b) c['a'] # returns 1 This has a few possible advantages, depending on your use-case.
1 Μαρ 2010 · For example, compare the output of pprint.pprint(person) using this approach, versus what you would have gotten had you used a regular python dict. Admittedly, you could fix that difference by adding a __repr__ method to the my_dict class
14 Αυγ 2010 · You could say defaultdict is useful for settings defaults before filling the dict and setdefault is useful for setting defaults while or after filling the dict. Probably the most common use case: Grouping items (in unsorted data, else use itertools.groupby)
In Python 2, you create two lists in memory for each dict, create a third list in memory with length equal to the length of the first two put together, and then discard all three lists to create the dict. In Python 3, this will fail because you're adding two dict_items objects together, not two lists - >>> c = dict(a.items() + b.items ...
4 Απρ 2020 · @schwobaseggl Part 1 = I think I get it. __dict__ stores things like self.name = name and self.height = height , and when i do object.__dict__ all those attributes that I had are stored into that dictionary where the key is the self.**name** (I mean only the bit after the dot) and the key is the value that was assigned to it.
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