Simplest way to iterate through a Multiset in the order of element frequency?

java guava multiset
Jonik picture Jonik · Dec 3, 2010 · Viewed 14.4k times · Source

Consider this example which prints out some device type stats. ("DeviceType" is an enum with a dozenish values.)

Multiset<DeviceType> histogram = getDeviceStats();
for (DeviceType type : histogram.elementSet()) {
    System.out.println(type + ": " + histogram.count(type));
}

What's the simplest, most elegant way to print the distinct elements in the order of their frequency (most common type first)?

With a quick look at the Multiset interface, there's no ready-made method for this, and none of Guava's Multiset implementations (HashMultiset, TreeMultiset, etc) seem to automatically keep elements frequency-ordered either.

Answer

Louis Wasserman picture Louis Wasserman · Sep 28, 2011

I just added this feature to Guava, see here for the Javadoc.

Edit: usage example of Multisets.copyHighestCountFirst() as per the original question:

Multiset<DeviceType> histogram = getDeviceStats();
for (DeviceType type : Multisets.copyHighestCountFirst(histogram).elementSet()) {
    System.out.println(type + ": " + histogram.count(type));
}

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