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  1. #1
    Goldstein is offline Member
    Join Date
    Feb 2012
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    Exclamation Map of words and their occurence [ Reverse Version ]

    Hey everyone,

    as written in the title im having trouble creating the reverse version of this code :
    for each word i associate its number of occurences.

    public static Map<String,Integer> orc(ArrayList<String> l)

    Map<String,Integer> m = new TreeMap<String,Integer>();
    for (int j=0; j < l.size() ; j++)
    int cpt=0;
    for (int i=0; i < l.size() ; i++)
    if ( l.get(i).equals(l.get(j)))
    m.put(l.get(j), cpt);
    return m;


    Now i want to create a map<Integer,Set<String>> which contains each number of occurence and the list of words who exists the same number of times:

    for example: 2 = { a,b,c} 1 = {d,e}

    Thank you :)

  2. #2
    pbrockway2 is offline Moderator
    Join Date
    Feb 2009
    New Zealand
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    Default Re: Map of words and their occurence [ Reverse Version ]

    Go through your first map and add for each string/count pair add it to the new map. Adding to the new map will involve (1) creating a new entry for that count if one does not already exist and (2) adding the string to the count's associated set.

    (I had a look at the extensive Guava library, but couldn't find a method that transforms maps like this. There is a MultiMap class, though, which allows duplicate values to be added.)

    [Edit] I knew I'd seen it somewhere! Guava does have an inverse() method - but only for ImmutableMultiMap<K,V>.
    Last edited by pbrockway2; 02-11-2012 at 10:54 PM.

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