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Counting values ​​of element values ​​inside a list inside a hash <String, List <String>>

I have a hash structure hash_feat <String, List<String>>, where my keys are Years , and in the values list contains a list of different terms.

I already have my hash, so that all elements from a certain key are in the same list for this key, for example:

<1997> <A,B,C,A,A,A,B,C,C,E> <2003> <C,C,C,A,B,A,D,D,D,A> <2004> <A,C,C,X,X,A,K,T,T,T>

I would like to have a count for each item. For 1997, A: 4, B: 2, C: 3, E: 1, etc., etc. For other keys .

I am trying to come up with this in order to use this “count” for later displaying on a figure, where I can visualize the highest values ​​for each element in the graph. This is probably not the smartest way, so any advice here is also welcome. The idea is to have a count of each item in my list so that I can manipulate / use in other methods.

Does anyone have any good advice on doing this in a reasonable way?

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3 answers

Here's a “simple” solution for Java 8:

import static java.util.stream.Collectors.*;

Map<String, Map<String, Long>> props =
  map.entrySet().stream().collect(toMap(Map.Entry::getKey,
    e -> e.getValue().stream().collect(groupingBy(String::toString, counting()))));

This will give you a map of years on a key map for counting.

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Eclipse Collections BagMultimap, . MutableBagMultimap .

MutableBagMultimap<String, String> multimap = Multimaps.mutable.bag.empty();
multimap.putAll("1997", Lists.mutable.with("A","B","C","A","A","A","B","C","C","E"));
multimap.putAll("2003", Lists.mutable.with("C","C","C","A","B","A","D","D","D","A"));
multimap.putAll("2004", Lists.mutable.with("A","C","C","X","X","A","K","T","T","T"));

Assert.assertEquals(4, multimap.get("1997").occurrencesOf("A"));
Assert.assertEquals(2, multimap.get("1997").occurrencesOf("B"));
Assert.assertEquals(3, multimap.get("1997").occurrencesOf("C"));
Assert.assertEquals(1, multimap.get("1997").occurrencesOf("E"));

multimap forEachKeyMultivalues toStringOfItemToCount.

multimap.forEachKeyMultiValues((key, values) ->
    System.out.println("<" + key + "> " + ((Bag<String>)values).toStringOfItemToCount()));

:

<1997> {E=1, A=4, B=2, C=3}
<2004> {T=3, A=2, C=2, X=2, K=1}
<2003> {D=3, A=3, B=1, C=3}

, forEachWithOccurrences, .

multimap.forEachKey(key -> {
    System.out.print(key + " ");
    multimap.get(key).forEachWithOccurrences((value, occurrences) ->
        System.out.print(value + ":" + occurrences + " "));
    System.out.println();
});

:

1997 E:1 A:4 B:2 C:3 
2004 T:3 A:2 C:2 X:2 K:1 
2003 D:3 A:3 B:1 C:3

, topOccurrences, , .

multimap.forEachKey(key -> {
    System.out.print(key + " ");
    MutableBag<String> bag = multimap.get(key);
    bag.topOccurrences(bag.sizeDistinct())
        .each(pair ->
            System.out.print(pair.getOne() + ":" + pair.getTwo() + " "));
    System.out.println();
});

:

1997 A:4 C:3 B:2 E:1 
2004 T:3 A:2 C:2 X:2 K:1 
2003 D:3 A:3 C:3 B:1

: Eclipse

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, - :

Map<String,List<String>> map = new HashMap<>();

, , :

for (List<String> values : map.values()){
    System.out.println(values.size());
}

If you need an account of each type inside the key, you need to check the type using values.get () and count each type.

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