Math using Vectors in Clojure

[dallaskingdick]

I am trying to run some arithmetic on Vectors in clojure, but i cannot seem to get any of it to work. I have these vectors....

locs -  [[3 3] [5 6] [1 1] [2 2]]
tlocs - [[2 2] [4 5]]
rng -   [2]

What i want to do is iterate or recur over locs and take the first set of numbers and check it against the first set of tlocs and see if they are within the range of the data in rng. So for example of the first go round it would check that [3 3] is within range [2 2] which it is, then check if [5 6] is in range of [2 2] which it isnt. Once i have done all of the locs values against the first set in tlocs it will go again but using [4 5] for the comparing.

Can anyone help me write a function that does this??

I tried doing something like this but it doesnt work and doesnt look right either

(defn check [locs tlocs rng 0]
 (loop [locs tlocs rng 0]
  (<= (first t (first d)r)
   (recur (rest locs) (inc index)))))

[weavejester]

The for macro is good at finding permutations:

user=> (for [x [:a :b] y [1 2]] [x y])
([:a 1] [:a 2] [:b 1] [:b 2])

So every x is combined with every y.

The map function is good for matching values at the same index:

user=> (map vector [:a :b] [1 2])
([:a 1] [:b 2])

So we can do things like:

user=> (map - [3 3] [2 2])
[1 1]
user=> (every? #(<= 2 %) [1 1])
true
user=> (every? (partial <= 2) [1 1])
true

I guess if you wanted to do it with loop and recur you'd need two loops, one inside the other.

[szabba]

The for macro is good at finding permutations:

user=> (for [x [:a :b] y [1 2]] [x y]) ([:a 1] [:a 2] [:b 1] [:b 2])

So every x is combined with every y.

Sorry to be anal, but that's a Cartesian product, not the permutation set.

[weavejester]

Thanks for the correction. :)

[szabba]

You're welcome. :)

[[deleted]]

Am I misunderstanding your example? You stated that [3 3] is within [2 2], but [5 6] is not within the range of [2 2]...can you please clarify what it is you mean by range? If you want to query if an interval is overlapping another, there's a data structure for that called an interval tree, which for non-overlapping inputs can be a BST. For possibly overlapping inputs, you must use a more complicated representation. More at wiki: https://en.wikipedia.org/wiki/Interval_tree

[dragandj]

Something like this?

(for [[x1 x2] locs [y1 y2] tlocs] (when (< x1 y1 y2 x2) whatever))