View Category
Numbers
Mathematical

Find the distance between two points

perl
use Math::Complex;
$a = Math::Complex->make(0, 3);
$b = Math::Complex->make(4, 0);
$distance = abs($a - $b);
java
double distance = Point2D.distance(x1, y1, x2, y2);
Point2D point1 = new Point2D.Double(x1, y1);
Point2D point2 = new Point2D.Double(x2, y2);
double distance = point1.distance(point2);
double distance = Math.hypot(x2-x1, y2-y1);
clojure
(defstruct point :x :y)

(defn distance
"Euclidean distance between 2 points"
[p1 p2]
(Math/pow (+ (Math/pow (- (:x p1) (:x p2)) 2)
(Math/pow (- (:y p1) (:y p2)) 2))
0.5))

(distance (struct point 0 0) (struct point 1 1)) ; => 1.4142135623730951
(defn distance
"Euclidean distance between 2 points"
[[x1 y1] [x2 y2]]
(Math/sqrt
(+ (Math/pow (- x1 x2) 2)
(Math/pow (- y1 y2) 2))))

(distance [2 2] [3 3])
fantom
px1 := 34.0f; py1 := 78.0f; px2 := 67.0f; py2 := -45.0f
distance := |Float x1, Float y1, Float x2, Float y2 -> Float|
{ ((x2-x1).pow(2.0f) + (y2-y1).pow(2.0f)).sqrt }

distance(px1, py1, px2, py2)
Output

Zero pad a number

Given the number 42, pad it to 8 characters like 00000042
perl
sprintf("%08d", 42);
java
String formatted = new DecimalFormat("00000000").format(42);
String formatted = String.format("%08d", 42);
clojure
(defn pad
([x] (if (> 8 (.length (str x))) (pad (str 0 x)) (str x)))
)
(defn pad [x]
(format "%08d" x))
(format "%08d" 42)
fantom
formatted := 42.toStr.padl(8, '0')
formatted := 42.toLocale("00000000")

Right Space pad a number

Given the number 1024 right pad it to 6 characters "1024  "
perl
sprintf("%-6d", 1024);
java
private static String spaces(int spaces) {
StringBuffer sb = new StringBuffer();
for(int i=0; i<spaces; i++) {
sb.append(' ');
}
return sb.toString();
}

private static String rightPad(int number, int spaces) {
String numberString = String.valueOf(number);
return numberString + spaces(spaces - numberString.length());
}
String text = StringUtils.rightPad(String.valueOf(1024), 6)
String formatted = String.format("%-6d", 1024);
clojure
(let [s (str 1024)
l (count s)]
(str s (reduce str (repeat (- 6 l) " "))))
fantom
formatted := 1024.toStr.padr(6)

Format a decimal number

Format the number 7/8 as a decimal with 2 places: 0.88
perl
sprintf("%.2f", 7/8);
java
String formatted = String.format("%3.2f", 7./8.);
clojure
(format "%3.2f" (/ 7.0 8))
(* 0.01 (Math/round (* 100 (float (/ 7 8)))))
fantom
formatted := (7.0/8.0).toLocale("0.00")

Left Space pad a number

Given the number 73 left pad it to 10 characters "        73"
perl
sprintf("%10d", 73);
java
private static String spaces(int spaces) {
StringBuffer sb = new StringBuffer();
for(int i=0; i<spaces; i++) {
sb.append(' ');
}
return sb.toString();
}

private static String leftPad(int number, int spaces) {
String numberString = String.valueOf(number);
return spaces(spaces - numberString.length()) + numberString;
}
String formatted = String.format("%10d", 73);
clojure
(let [s (str 73)
l (count s)]
(str (reduce str (repeat (- 10 l) " ")) s ))
fantom
formatted := 73.toStr.padl(10)
Random

Generate a random integer in a given range

Produce a random integer between 100 and 200 inclusive
perl
my $range = 100;
my $minimum = 100;

my $random_number = int(rand($range)) + $minimum;

print "$random_number\n";
java
Random random = new Random();
int randomInt = random.nextInt(200-100+1)+100;
clojure
(+ (rand-int (- 201 100)) 100)
fantom
r := Int.random(100..200)

Generate a repeatable random number sequence

Initialise a random number generator with a seed and generate five decimal values. Reset the seed and produce the same values.
perl
srand(12345);
@list1 = map(int(rand(100)+1), (1..5));

srand(12345);
@list2 = map(int(rand(100)+1), (1..5));

print join(', ', @list1) . "\n";
print join(', ', @list2) . "\n";
java
int[] arr1 = genFillRand(new int[5], new Random(12345), 100, 200);
int[] arr2 = genFillRand(new int[5], new Random(12345), 100, 200);

for (int[] arr : new int[][]{ arr1, arr2 }) { for (int i : arr) System.out.printf("%d ", i); System.out.println(); }
clojure
(dotimes [_ 2]
(let [r (java.util.Random. 12345)]
(dotimes [_ 5]
(println (.nextInt r 100))))
(println))
fantom
rand := Random.makeSeeded(12345)
first := Int[,].fill(0,5).map { rand.next(100..200) }

rand2 := Random.makeSeeded(12345)
second := Int[,].fill(0,5).map { rand2.next(100..200) }