c# get value subset from dictionary by keylist

Question

Ok, so you can get a single value by dictionary[key] or all values by dictionary.Values.

What I am looking for is a way to get all values for a given key set like so:

List<string> keys;
Dictionary<string, object> dictionary;

List<object> valuesForKeys = GetValuesFromDictionaryUsingKeys(dictionary, keys);

with

private List<object> GetValuesFromDictionaryUsingKeys(Dictionary<string, object> dictionary, List<string> keys)
{
    //your code here
}

Of course I could iterate manually over the keylist and use dictionary[key] each time and add all the values back to a list again, but I would like to use some more elegant way (e.g. Linq).

Thanks.

Answer 1

Why write function when you can have generic extension method for everyday use?

public static IEnumerable<V> GetValues<K, V>(this IDictionary<K, V> dict, IEnumerable<K> keys)
{
    return keys.Select((x) => dict[x]);
}

EDIT: Than you can write:

var  valuesForKeys = dictionary.GetValues(keys).ToList();

Answer 2

Try keys.Where(k => dictionary.ContainsKey(k)).Select(k => dictionary[k]).