On Tue, Jun 2, 2009 at 5:35 PM, Wilson MacGyver <[email protected]> wrote:
>
> Apologies in advance on a very newbie question.
>
> I've constructed a sequence
>
> (take 10 (iterate (fn [[a b]] [(* 2 a) (/ a (Math/log a))]) [2 (/ 2
> (Math/log 2))])
>
> doing a take 10 on it, produce the pairs I expect.
>
> what I like to know is, how do I filter for with value b is < X
>
> for example, the first 10 produces.
>
> ([2 2.8853900817779268] [4 2.8853900817779268] [8 2.8853900817779268]
> [16 3.8471867757039027] [32 5.7707801635558535] [64 9.233248261689365]
> [128 15.38874710281561] [256 26.380709319112476] [512
> 46.16624130844683] [1024 82.07331788168325])
>
> what if I want to filter so I only get pairs for which the 2nd value
> is < 10. I couldn't figure out how to get
> filter to work for pair values.
How about:
(take-while (fn [[a b]] (< b 10))
(iterate (fn [[a b]] [(* 2 a) (/ a (Math/log a))])
[2 (/ 2 (Math/log 2))]))
> a 2nd question is more of general clojure idiom, in trying to covert
> the following java
> code from michaelg's java 1 presentation
>
> private int calcSize(){
> int max = 2;
> while ((max/Math.log(max)) < size &&
> max < Integer.MAX_VALUE && max > 0){
> max *=2;
> }
> return max;
> }
>
> My first reaction was to do it using a sequence. Is this the clojure
> idiomatic way to convert a
> while loop from other languages?
I suppose it would depend on the loop, but yes, I think so.
--
Michael Wood <[email protected]>
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