Tutorial by Examples: dict

In SQLAlchemy core, the result is RowProxy. In cases where you want an explicit dictionary, you can call dict(row). First the setup for the example: import datetime as dt from sqlalchemy import ( Column, Date, Integer, MetaData, Table, Text, create_engine, select) metadata = MetaData() u...

Each pair in the dictionary is an instance of KeyValuePair with the same type parameters as the Dictionary. When you loop through the dictionary with For Each, each iteration will give you one of the Key-Value Pairs stored in the dictionary. For Each kvp As KeyValuePair(Of String, String) In curren...

Dim extensions As New Dictionary(Of String, String) _ from { { "txt", "notepad" }, { "bmp", "paint" }, { "doc", "winword" } } This creates a dictionary and immediately fills it with three KeyValuePairs. You can also add new val...

Dictionaries are implemented in a Dict core library. A dictionary mapping unique keys to values. The keys can be any comparable type. This includes Int, Float, Time, Char, String, and tuples or lists of comparable types. Insert, remove, and query operations all take O(log n) time. Unlike Tu...

You can use the ** keyword argument unpacking operator to deliver the key-value pairs in a dictionary into a function's arguments. A simplified example from the official documentation: >>> >>> def parrot(voltage, state, action): ... print("This parrot wouldn't", ac...

Consider the following dictionaries: >>> fish = {'name': "Nemo", 'hands': "fins", 'special': "gills"} >>> dog = {'name': "Clifford", 'hands': "paws", 'color': "red"} Python 3.5+ >>> fishdog = {**fish, **dog}...

You can get the value of an entry in the dictionary using the 'Item' property: Dim extensions As New Dictionary(Of String, String) From { { "txt", "notepad" }, { "bmp", "paint" }, { "doc", "winword" } } Dim program As St...

options = { "x": ["a", "b"], "y": [10, 20, 30] } Given a dictionary such as the one shown above, where there is a list representing a set of values to explore for the corresponding key. Suppose you want to explore "x"="a" w...

If you use a dictionary as an iterator (e.g. in a for statement), it traverses the keys of the dictionary. For example: d = {'a': 1, 'b': 2, 'c':3} for key in d: print(key, d[key]) # c 3 # b 2 # a 1 The same is true when used in a comprehension print([key for key in d]) # ['c', 'b', '...

Prefer dict.get method if you are not sure if the key is present. It allows you to return a default value if key is not found. The traditional method dict[key] would raise a KeyError exception. Rather than doing def add_student(): try: students['count'] += 1 except KeyError: ...

+ dictionaryWithCapacity: Creates and returns a mutable dictionary, initially giving it enough allocated memory to hold a given number of entries. NSMutableDictionary *dict = [NSMutableDictionary dictionaryWithCapacity:1]; NSLog(@"%@",dict); - init Initializes a newly allocated mut...

- removeObjectForKey: Removes a given key and its associated value from the dictionary. NSMutableDictionary *dict = [NSMutableDictionary dictionaryWithDictionary:@{@"key1":@"Easy",@"key2": @"Tutorials"}]; [dict removeObjectForKey:@"key1"]; NSLog...

Rules for creating a dictionary: Every key must be unique (otherwise it will be overridden) Every key must be hashable (can use the hash function to hash it; otherwise TypeError will be thrown) There is no particular order for the keys. # Creating and populating it with values stock = {'egg...

def foobar(foo=None, bar=None): return "{}{}".format(foo, bar) values = {"foo": "foo", "bar": "bar"} foobar(**values) # "foobar"

Dictionary<TKey, TValue> is a map. For a given key there can be one value in the dictionary. using System.Collections.Generic; var people = new Dictionary<string, int> { { "John", 30 }, {"Mary", 35}, {"Jack", 40} }; // Reading data Console.Wri...

Objective c: //this is the dictionary you start with. NSDictionary *dict = [NSDictionary dictionaryWithObjectsAndKeys:@"name1", @"Sam",@"name2", @"Sanju",nil]; //check if the dictionary contains the key you are going to modify. In this example, @&qu...

Functions allow you to specify these types of parameters: positional, named, variable positional, Keyword args (kwargs). Here is a clear and concise use of each type. def unpacking(a, b, c=45, d=60, *args, **kwargs): print(a, b, c, d, args, kwargs) >>> unpacking(1, 2) 1 2 45 60 ()...

Subscripts can also be used with NSDictionary and NSMutableDictionary. The following code: NSMutableDictionary *myDictionary = [@{@"Foo": @"Bar"} mutableCopy]; [myDictionary setObject:@"Baz" forKey:@"Foo"]; NSLog(@"%@", [myDictionary objectForKey:...

Create a Dictionary<TKey, TValue> from an IEnumerable<T>: using System; using System.Collections.Generic; using System.Linq; public class Fruits { public int Id { get; set; } public string Name { get; set; } } var fruits = new[] { new Fruits { Id = 8 , Nam...

Starting from a dataframe df: U L 111 en 112 en 112 es 113 es 113 ja 113 zh 114 es Imagine you want to add a new column called S taking values from the following dictionary: d = {112: 'en', 113: 'es', 114: 'es', 111: 'en'} You can use map to perform a lookup on keys returni...