Re: counting quotations by author
In article <494a882c$0$16615$7836cce5@newsrazor.net>,
Daniel Pitts <newsgroup.spamfilter@virtualinfinity.net> wrote:
John B. Matthews wrote:
In article <8u6kk49i5k83clrmkq83ehqjn1omof33pj@4ax.com>,
Roedy Green <see_website@mindprod.com.invalid> wrote:
On Thu, 18 Dec 2008 09:31:59 +0000, RedGrittyBrick
<RedGrittyBrick@spamweary.invalid> wrote, quoted or indirectly quoted
someone who said :
In order to avoid a separate sort step, I'd maintain RankedAuthor in
sorted order as authors are added and as authors' counts are
incremented. I guess this would require using a linked list or some
suitable Collection such as SortedSet with an implementation of
Comparator in RankedAuthor.
the count then would have to be part of the key. Are you allowed to
change keys on existing records in a TreeMap or TreeSet?
Given a TreeMap<String, Integer>, entries would be sorted according to
the natural order for the key's class, String. Instead, you can
construct the TreeMap with a Comparator that implements compare() &
equals() with respect to the value's class, Integer.
Roedy's point (and it is a valid one) is that you cannot modify a key
after it has been added.
Good point. A TreeMap constructed with a Comparator<Integer> would be
terrible for looking up authors by name. I plead inanity [sic].
You *can* avoid the last sort step, but it seems to me that unless you
have millions of authors, it wouldn't be worth optimizing. I don't even
know that avoiding a sort would give you that much of a gain.
public class Author {
private final String name;
private int referenceCount;
}
public class Book {
public List<Author> getRankedAuthors() {
final Map<String, Author> authorMap = new HashMap<String, Author>();
countReferences(authorMap);
final List<Author> rankedAuthors =
new ArrayList<Author>(authorMap.values());
Collections.sort(rankedAuthors,
new AuthorReferenceCountComparator());
return rankedAuthors;
}
}
Much clearer!
--
John B. Matthews
trashgod at gmail dot com
http://home.roadrunner.com/~jbmatthews/