Use LINQ to omit some entries in the value part of a dictionary and project this into a new dictonary maintaing original keys.

Question

Hi All,

I have a generic dictonary which is templated in the following manner:

Dictionary<object, IList<ISomeInterface>> dictionary1 = new Dictionary<object,    IList<ISomeInterface>>();

If I wanted to omit certain list items against arbitrary keys (that is the items that are in the list contained within the value part of each of the key value pairs making up the dictionary) given some arbitrary condition (lets say omitting list items where a list item contained the string "abc")

I would expect to able to create/project into a new dictionary which would contain entries which contained lists WITHOUT those items whose name contained "abc"

How do I achieve this using a Lambda expression?

I was trying something like this:

var result1 = dictionary1.Where(x => x.Value == x.Value.Select(y => !y.contains("abc"));

Answer 1

To you want it as another dictionary? Try this:

var result = original.ToDictionary(
    pair => pair.Key, // Key in result is key in original
    value => pair.Value  // Value in result is query on original value
                 .Where(item => !item.Contains("abc").ToList());

EDIT: VB as per the comment:

someDictionary.ToDictionary(Function(x) x.key, _ 
            Function(y) y.Value.Where(not y.Value contains("abc").ToList())

Answer 2

var result1 = dictionary1.Select(x => 
     {
          return new KeyValuePair<object, IList<ISomeInterface>>(
                     x.Key, 
                     x.Value.Where(y => y.Contains("abc")).ToList());
     }).ToDictionary(item => item.Key, item => item.Value);