Like this: keys = [‘a’, ‘b’, ‘c’] values = [1, 2, 3] dictionary = dict(zip(keys, values)) print(dictionary) # {‘a’: 1, ‘b’: 2, ‘c’: 3} Voila 🙂 The pairwise dict constructor and zip function are awesomely useful.
There are some good answers here. I would add to them the following points. What is the correct C# way of representing a data structure, which, “logically” (that is to say, “to the human mind”) is just a list of things with a few bells and whistles? Ask any ten non-computer-programmer people who are familiar … Read more
There are several ways of checking if an variable is an array or not. The best solution is the one you have chosen. variable.constructor === Array This is the fastest method on Chrome, and most likely all other browsers. All arrays are objects, so checking the constructor property is a fast process for JavaScript engines. … Read more
It’s because any iterable can be joined (e.g, list, tuple, dict, set), but its contents and the “joiner” must be strings. For example: ‘_’.join([‘welcome’, ‘to’, ‘stack’, ‘overflow’]) ‘_’.join((‘welcome’, ‘to’, ‘stack’, ‘overflow’)) ‘welcome_to_stack_overflow’ Using something other than strings will raise the following error: TypeError: sequence item 0: expected str instance, int found
If you only want a single item’s count, use the count method: >>> [1, 2, 3, 4, 1, 4, 1].count(1) 3 Important: this is very slow if you are counting multiple different items Each count call goes over the entire list of n elements. Calling count in a loop n times means n * n … Read more
Use del and specify the index of the element you want to delete: >>> a = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9] >>> del a[-1] >>> a [0, 1, 2, 3, 4, 5, 6, 7, 8] Also supports slices: >>> del a[2:4] >>> a [0, 1, 4, 5, 6, 7, 8, … Read more
The len() function can be used with several different types in Python – both built-in types and library types. For example: >>> len([1, 2, 3]) 3
Use random.choice(): import random foo = [‘a’, ‘b’, ‘c’, ‘d’, ‘e’] print(random.choice(foo)) For cryptographically secure random choices (e.g., for generating a passphrase from a wordlist), use secrets.choice(): import secrets foo = [‘battery’, ‘correct’, ‘horse’, ‘staple’] print(secrets.choice(foo)) secrets is new in Python 3.6. On older versions of Python you can use the random.SystemRandom class: import random … Read more
The sorted() function takes a key= parameter newlist = sorted(list_to_be_sorted, key=lambda d: d[‘name’]) Alternatively, you can use operator.itemgetter instead of defining the function yourself from operator import itemgetter newlist = sorted(list_to_be_sorted, key=itemgetter(‘name’)) For completeness, add reverse=True to sort in descending order newlist = sorted(list_to_be_sorted, key=itemgetter(‘name’), reverse=True)
some_list[-1] is the shortest and most Pythonic. In fact, you can do much more with this syntax. The some_list[-n] syntax gets the nth-to-last element. So some_list[-1] gets the last element, some_list[-2] gets the second to last, etc, all the way down to some_list[-len(some_list)], which gives you the first element. You can also set list elements … Read more