Several mistakes (updated)

mistakes — cgrand, 18 June 2008 @ 16 h 05 min

In the previous post, there were several mistakes. They are all fixed by now, except one:

(defn top [n h]
  (take n (sort #(- (val %2) (val %1)) h)))

Yup, this code is buggy: it is intended to sort hash entries by descending val order (values are numbers) and it breaks on large data sets.
With large data sets, some values get big and doesn’t fit into an int anymore while some stay small thus the difference of such two numbers doesn’t fit into an int while Comparator.compare must return an int: overflow.
Here is one way to fix that:

(defn top [n h]
  (take n (sort #(.compare clojure.lang.Numbers (val %2) (val %1)) h)))

I have hope that there will be a better way to fix that in a near future.

(defn top [n h]
  (take n (sort #(compare (val %2) (val %1)) h)))

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