Python dictionaries don’t support duplicate keys. One way around is to store lists or sets inside the dictionary. One easy way to achieve this is by using defaultdict: from collections import defaultdict data_dict = defaultdict(list) All you have to do is replace data_dict[regNumber] = details with data_dict[regNumber].append(details) and you’ll get a dictionary of lists.
You could try: dict((k, bigdict[k]) for k in (‘l’, ‘m’, ‘n’)) … or in Python 3 Python versions 2.7 or later (thanks to Fábio Diniz for pointing that out that it works in 2.7 too): {k: bigdict[k] for k in (‘l’, ‘m’, ‘n’)} Update: As Håvard S points out, I’m assuming that you know the … Read more
You can iterate over the dictionaries directly — no need to use range. The setdefault method of dict looks up a key, and returns the value if found. If not found, it returns a default, and also assigns that default to the key. super_dict = {} for d in dicts: for k, v in d.iteritems(): … Read more
As mentioned in the Xcode 6 beta 6 release notes, a large number of Foundation APIs have been audited for optional conformance. These changes replace T! with either T? or T depending on whether the value can be null (or not) respectively. notification.userInfo is now an optional dictionary: class NSNotification : NSObject, NSCopying, NSCoding { … Read more
You could write your own read-only wrapper for the dictionary, e.g.: public class ReadOnlyDictionaryWrapper<TKey, TValue, TReadOnlyValue> : IReadOnlyDictionary<TKey, TReadOnlyValue> where TValue : TReadOnlyValue { private IDictionary<TKey, TValue> _dictionary; public ReadOnlyDictionaryWrapper(IDictionary<TKey, TValue> dictionary) { if (dictionary == null) throw new ArgumentNullException(“dictionary”); _dictionary = dictionary; } public bool ContainsKey(TKey key) { return _dictionary.ContainsKey(key); } public IEnumerable<TKey> Keys … Read more
You can just add a computed property to your struct to return a Dictionary with your values. Note that Swift native dictionary type doesn’t have any method called value(forKey:). You would need to cast your Dictionary to NSDictionary: struct Test { let name: String let age: Int let height: Double var dictionary: [String: Any] { … Read more
If the data is tokenized (i.e. “Dear $name$, as of $date$ your balance is $amount$”), then a Regex can be useful: static readonly Regex re = new Regex(@”\$(\w+)\$”, RegexOptions.Compiled); static void Main() { string input = @”Dear $name$, as of $date$ your balance is $amount$”; var args = new Dictionary<string, string>( StringComparer.OrdinalIgnoreCase) { {“name”, “Mr … Read more
When working with dictionaries you have to remember that a key might not exist in the dictionary. For this reason, dictionaries always return optionals. So each time you access the dictionary by key you have to unwrap at each level as follows: bugsDict[“ladybug”]![“spotted”]![“red”]!++ I presume you know about optionals, but just to be clear, use … Read more
No, there is nothing faster than a dictionary for this task and that’s because the complexity of its indexing (getting and setting item) and even membership checking is O(1) in average. (check the complexity of the rest of functionalities on Python doc https://wiki.python.org/moin/TimeComplexity ) Once you saved your items in a dictionary, you can have … Read more
Use csv.DictReader: import csv with open(‘test.csv’) as f: a = [{k: int(v) for k, v in row.items()} for row in csv.DictReader(f, skipinitialspace=True)] Will result in : [{‘col2’: 2, ‘col3’: 3, ‘col1’: 1}, {‘col2’: 5, ‘col3’: 6, ‘col1’: 4}]