Entropy/Narcissist: Difference between revisions

=={{header|Kotlin}}==

<lang scala>// version 1.1.0 (entropy_narc.kt)

fun log2(d: Double) = Math.log(d) / Math.log(2.0)

fun shannon(s: String): Double {

val counters = mutableMapOf<Char, Int>()

for (c in s) {

if (counters.containsKey(c)) counters[c] = counters[c]!! + 1

else counters.put(c, 1)

}

val nn = s.length.toDouble()

var sum = 0.0

for (key in counters.keys) {

val term = counters[key]!! / nn

sum += term * log2(term)

}

return -sum

}

fun main(args: Array<String>) {

val prog = java.io.File("entropy_narc.kt").readText()

println("This program's entropy is ${"%18.16f".format(shannon(prog))}")

}</lang>

{{out}}

<pre>

This program's entropy is 4.8471803665906705

</pre>