Code samples for blog post on list comprehensions

comprehension1.clj

(defn euclidean [x y] (Math/sqrt (+ (Math/pow x 2) (Math/pow y 2))))

(println (for [
	 [x,y] 
	 [[1,2],[2,3],[3,4]] 
	 :when (> (euclidean x y) 3.0)] 
	 [(euclidean x y),(Math/toDegrees (Math/atan (/ y x)))]))

comprehension1.hs

toDegrees :: Floating a => a -> a
toDegrees rad = rad * 180 / pi

euclidean :: Floating a => a -> a -> a
euclidean x y = let foo = x ^^ 2
	      	    bar = y ^^ 2 
		in sqrt (foo + bar)

main = do
     print [(euclidean x y,(toDegrees . atan) (y / x))|(x,y)<-[(1,2),(2,3),(3,4)],(euclidean x y) > 3.0]

comprehension1.py

from math import sqrt, atan, degrees

def euclidean(x,y):
    return sqrt(x**2 + y**2)

print [(euclidean(x,y),degrees(atan(float(y)/x))) for (x,y) in [(1,2),(2,3),(3,4)] if euclidean(x,y) > 3.0]

comprehension1.scala

import scala.math.{atan,pow,sqrt,toDegrees}

def euclidean(x:Int,y:Int) = sqrt(pow(x,2) + pow(y,2))

val result =
  for {
    (x,y) <- List((1,2),(2,3),(3,4))
    if (euclidean(x,y) > 3.0) }
  yield (euclidean(x,y),toDegrees(atan(y.toFloat/x)))
println(result)

comprehension2.clj

(defn euclidean [x y] (Math/sqrt (+ (Math/pow x 2) (Math/pow y 2))))

(println (for [
	 [x,y] 
	 [[1,2],[2,3],[3,4]] 
	 :let [dist (euclidean x y)] 
	 :when (> dist 3.0)]
	 [dist,(Math/toDegrees (Math/atan (/ y x)))]))

comprehension2.hs

toDegrees :: Floating a => a -> a
toDegrees rad = rad * 180 / pi

euclidean :: Floating a => a -> a -> a
euclidean x y = let foo = x ^^ 2
	      	    bar = y ^^ 2 
		in sqrt (foo + bar)

main = do
     print [(dist,(toDegrees . atan) (y / x))|(x,y)<-[(1,2),(2,3),(3,4)],let dist=euclidean x y,dist > 3.0]

comprehension2.scala

import scala.math.{atan,pow,sqrt,toDegrees}

def euclidean(x:Int,y:Int) = sqrt(pow(x,2) + pow(y,2))

val result = 
  for {
    (x,y) <- List((1,2),(2,3),(3,4))
    dist = euclidean(x,y)
    if dist > 3.0 }
  yield (dist,toDegrees(atan(y.toFloat/x)))
println(result)

solution1.py

from math import sqrt, atan, degrees
data=[(1,2),(2,3),(3,4)]
print [(dist,degrees) for (dist,degrees) in [(sqrt(x**2 + y**2),degrees(atan(float(y)/x))) for (x,y) in data] if dist > 3.0]

solution2.py

from math import sqrt, atan, degrees
data=[(1,2),(2,3),(3,4)]
def somefunc(alist):
    for (x,y) in alist:
	dist = sqrt(x**2 + y**2)
	if (dist > 3.0):
            yield (dist,degrees(atan(float(y)/x)))
print list(somefunc(data))