Finding most approximated item in collection object?

  • Thread starter Thread starter Hyun-jik Bae
  • Start date Start date
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Hyun-jik Bae

Is there any way how to get the item which has the most similar key in
key-value collection object such as Dictionary<> or SortedDictionary<>
although there is no matching key? If there is none, is there any
substitution class for enabling this?

Please reply. Thanks in advance.

Hyun-jik Bae
 
to my understanding you are asking about a way to match the keys as such

key = "test"
if test is there then you should get the value of it and else you should get
the value of a key that has "testdata" I am I correct..

If yes then this is not possible and key has to match exactly. If you need
some thing like this then you may have to write a collection that does this
for you by probably exrednign the existing one.

Nirosh.
 
You're talking about some fuzzy logic there - first and most importantly you
need to define exactly what "most similar" means, between whatever objects
you're comparing. From there you would probably implement IComparer for the
type and a custom collection that would allow this fuzzy lookup.

For example for String, you could define "most similar" as the first match
less than or equal to a given value, then using a sorted set of values
(untested code here)...

string find = "d";
string[] values = { "a", "c", "e" };
string match = null;

Array.Sort(values);

foreach(string s in values)
{
if (s.CompareTo(find) <= 0)
{
match = s;
break;
}
}
 
Hi Hyun-jik,

You can subclass Dictionary or SortedDictionary and add your own property to
iterate the Keys collection and return an appropriate value, however you won't
be able to modify the indexer to match similar values. If the hash codes
aren't consistent with the equality comparison then you won't be able to
locate existing keys in the Dictionary.
 
Hyun-jik Bae said:
Is there any way how to get the item which has the most similar key in
key-value collection object such as Dictionary<> or SortedDictionary<>
although there is no matching key? If there is none, is there any
substitution class for enabling this?
Click to expand...

Take a look at the Dictionary (IEqualityComparer<T>) constructor which
allows you to specify custom Equals and GetHashCode methods.

This may not be what you want, though. I get the impression (though I
may be wrong) that you only want to match, say, "Schmidt" if "Smith"
isn't found, while using an IEqualityComparer will always equate
"Schmidt" with "Smith."
 
Hyun-jik Bae said:
Is there any way how to get the item which has the most similar key in
key-value collection object such as Dictionary<> or SortedDictionary<>
although there is no matching key? If there is none, is there any
substitution class for enabling this?
Click to expand...

I don't see anyway except to iterate through the entire collection and apply
a comparison yourself. You'd have to rank items by similarity, sort them and
take the highest (or lowest) value.
 
Hi,

What is the problem that you have? maybe we can help you get a better
solution than the one you are expecting to use
 
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