The del statement removes an element: del d[key] Note that this mutates the existing dictionary, so the contents of the dictionary changes for anybody else who has a reference to the same instance. To return a new dictionary, make a copy of the dictionary: def removekey(d, key): r = dict(d) del r[key] return r The … Read more
There are two built-in functions that help you identify the type of an object. You can use type() if you need the exact type of an object, and isinstance() to check an object’s type against something. Usually, you want to use isinstance() most of the times since it is very robust and also supports type … 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)
To delete a key regardless of whether it is in the dictionary, use the two-argument form of dict.pop(): my_dict.pop(‘key’, None) This will return my_dict[key] if key exists in the dictionary, and None otherwise. If the second parameter is not specified (i.e. my_dict.pop(‘key’)) and key does not exist, a KeyError is raised. To delete a key … Read more
in tests for the existence of a key in a dict: d = {“key1”: 10, “key2”: 23} if “key1” in d: print(“this will execute”) if “nonexistent key” in d: print(“this will not”) Use dict.get() to provide a default value when the key does not exist: d = {} for i in range(10): d[i] = d.get(i, … Read more
foreach(KeyValuePair<string, string> entry in myDictionary) { // do something with entry.Value or entry.Key }
You create a new key/value pair on a dictionary by assigning a value to that key d = {‘key’: ‘value’} print(d) # {‘key’: ‘value’} d[‘mynewkey’] = ‘mynewvalue’ print(d) # {‘key’: ‘value’, ‘mynewkey’: ‘mynewvalue’} If the key doesn’t exist, it’s added and points to that value. If it exists, the current value it points to is … Read more
Python 3.7+ or CPython 3.6 Dicts preserve insertion order in Python 3.7+. Same in CPython 3.6, but it’s an implementation detail. >>> x = {1: 2, 3: 4, 4: 3, 2: 1, 0: 0} >>> {k: v for k, v in sorted(x.items(), key=lambda item: item[1])} {0: 0, 2: 1, 1: 2, 4: 3, 3: 4} … Read more
Map<String, String> map = … for (Map.Entry<String, String> entry : map.entrySet()) { System.out.println(entry.getKey() + “/” + entry.getValue()); } On Java 10+: for (var entry : map.entrySet()) { System.out.println(entry.getKey() + “/” + entry.getValue()); }