(ns code.utils.mw
  (:use (incanter core stats)))


(defn mw [a b] ;a and b are already ranked
	(let [asum (apply + a)
				bsum (apply + b)
				na (count a)
				nb (count b)
				n (+ na nb)
				amedrank (median a)
				bmedrank (median b)
				rank-asum (/ (* na (+ n 1)) 2)
				rank-bsum (/ (* nb (+ n 1)) 2)
				stdev (sqrt (/ (* na nb (+ n 1)) 12.0))
				z (fn [rsum msum]
						(if (< rsum msum)
							(/ (+ (- rsum msum) 0.5) stdev)
              (/ (- (- rsum msum) 0.5) stdev)))
        za (z asum rank-asum)
        zb (z bsum rank-bsum)
        Z  (if (> za zb) za zb)]
		(if (and (<= Z 1.96) (>= Z 0))
			'high
  		(if (> amedrank bmedrank)
  		   'high
  		   (if (< amedrank bmedrank)
  		    'low
  		    'high)))))

(defn mw-2 [a b] ;a and b are already ranked
	(let [asum (apply + a)
				bsum (apply + b)
				na (count a)
				nb (count b)
				n (+ na nb)
				rank-asum (/ (* na (+ n 1)) 2)
				rank-bsum (/ (* nb (+ n 1)) 2)
				stdev (sqrt (/ (* na nb (+ n 1)) 12.0))
				z (fn [rsum msum]
						(if (< rsum msum)
							(/ (+ (- rsum msum) 0.5) stdev)
              (/ (- (- rsum msum) 0.5) stdev)))
        za (z asum rank-asum)
        zb (z bsum rank-bsum)
        Z  (if (> za zb) za zb)]
		(if (and (<= Z 1.96) (>= Z 0))
			'high
  		'low)))
  		
(defn mw-1 [a b] ;a and b are already ranked
	(let [asum (apply + a)
				bsum (apply + b)
				na (count a)
				nb (count b)
				n (+ na nb)
				rank-asum (/ (* na (+ n 1)) 2)
				rank-bsum (/ (* nb (+ n 1)) 2)
				stdev (sqrt (/ (* na nb (+ n 1)) 12.0))
				z (fn [rsum msum]
						(if (< rsum msum)
							(/ (+ (- rsum msum) 0.5) stdev)
              (/ (- (- rsum msum) 0.5) stdev)))
        za (z asum rank-asum)
        zb (z bsum rank-bsum)
        Z  (if (> za zb) za zb)]
		(if (and (<= Z 1.96) (>= Z 0))
			0
  		(if (< za zb) -1 1))))  		
  		
 		
(defn mw-0 [a b] ;a and b are already ranked
	(let [asum (apply + a)
				bsum (apply + b)
				na (count a)
				nb (count b)
				n (+ na nb)
				amedrank (median a)
				bmedrank (median b)
				rank-asum (/ (* na (+ n 1)) 2)
				rank-bsum (/ (* nb (+ n 1)) 2)
				stdev (sqrt (/ (* na nb (+ n 1)) 12.0))
				z (fn [rsum msum]
						(if (< rsum msum)
							(/ (+ (- rsum msum) 0.5) stdev)
              (/ (- (- rsum msum) 0.5) stdev)))
        za (z asum rank-asum)
        zb (z bsum rank-bsum)
        Z  (if (> za zb) za zb)]
		(if (and (<= Z 1.96) (>= Z 0))
			0
  		(if (> amedrank bmedrank)
  		   1
  		   (if (< amedrank bmedrank)
  		    -1
  		    1)))))