Data Strucutre for non-unique key-value pairs

[jyohere]

I have a problem....I want to know what is the data structure that can be used to store non-unique key -value pairs.....espec ially non-unique keys.....HashMa p cannot be used, right....since it holds only unique keys...pls help

[JosAH]

I have a problem....I want to know what is the data structure that can be used to store non-unique key -value pairs.....espec ially non-unique keys.....HashMa p cannot be used, right....since it holds only unique keys...pls help

Instead of key-value pairs think of key-values (plural), so the value object in
your Map is actually a List or Set holding all the values associated with a key.

kind regards,

Jos

[r035198x]

I have a problem....I want to know what is the data structure that can be used to store non-unique key -value pairs.....espec ially non-unique keys.....HashMa p cannot be used, right....since it holds only unique keys...pls help

You'll have to make your own type which is not a map.

From the docs

A map cannot contain duplicate keys; each key can map to at most one value.

[beatTheDevil]

Well of course you could hack it and use a Map as Jos suggested. Simply encapsulate your multiple values into a single Object of some kind (a List, Set, Array, etc.) and store that as your value. Makes your life a bit more difficult, but you could get it to work easily enough. To be super-clear, your mappings would take the form:

<key, List(value 1, value 2, ..., value n)>

Making your own data structure is only worth it if:
a) this is a major and reusable component in your application
b) you have a good algorithm + data structure in mind that will perform better than the above "hack"

[jyohere]

Well of course you could hack it and use a Map as Jos suggested. Simply encapsulate your multiple values into a single Object of some kind (a List, Set, Array, etc.) and store that as your value. Makes your life a bit more difficult, but you could get it to work easily enough. To be super-clear, your mappings would take the form:

<key, List(value 1, value 2, ..., value n)>

Making your own data structure is only worth it if:
a) this is a major and reusable component in your application
b) you have a good algorithm + data structure in mind that will perform better than the above "hack"

That was great....it worked thaannnnnnnnnnn x......

[sendit34]

can you put the implemantation code of this senerio here?



may be something like this ?

http://www.codeproject.com/useritems/Multi-Index_Container.asp

or you have some oyher impl?


Thanks,

[JosAH]

can you put the impemantation code of this senerio here?

Thanks,

The code doesn't take many more characters than this message; the clue
has been given to you already also. What do you want that code for? Hint: it's
a Map taking a type K key and a type List<V> for the values; each value is of
type V.

kind regards,

Jos