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Unbias a random generator: Difference between revisions
Added Julia language
(=={{header|Julia}}=={{works with|Julia|0.6}}<lang julia></lang>{{out}}<pre></pre>) |
(Added Julia language) |
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</pre>
=={{header|
{{works with|Julia|0.6}}
<lang julia>randN(N) = () -> rand(1:N) == 1 ? 1 : 0
function unbiased(biased::Function)
this, that = biased(), biased()
while this == that this, that = biased(), biased() end
return this
end
@printf "%2s | %10s | %5s | %5s | %8s" "N" "bias./unb." "1s" "0s" "pct ratio"
const nrep = 10000
for N in 3:6
biased = randN(N)
v = collect(biased() for __ in 1:nrep)
v1, v0 = count(v
@printf("%2i | %10s | %5i | %5i | %5.2f%%\n", N, "biased", v1, v0, 100 * v1 / nrep)
v = collect(unbiased(biased) for __ in 1:nrep)
v1, v0 = count(v .== 1), count(v .== 0)
@printf("%2i | %10s | %5i | %5i | %5.2f%%\n", N, "unbiased", v1, v0, 100 * v1 / nrep)
end</lang>
{{out}}
<pre> N | bias./unb. | 1s | 0s | pct ratio
3 | biased | 3286 | 6714 | 32.86%
3 | unbiased | 4986 | 5014 | 49.86%
4 | biased | 2473 | 7527 | 24.73%
4 | unbiased | 4986 | 5014 | 49.86%
5 | biased | 1992 | 8008 | 19.92%
5 | unbiased | 5121 | 4879 | 51.21%
6 | biased | 1663 | 8337 | 16.63%
6 | unbiased | 5040 | 4960 | 50.40%</pre>
=={{header|Kotlin}}==
{{trans|Java}}
<lang scala>// version 1.1.2
fun biased(n: Int) = Math.random() < 1.0 / n
fun unbiased(n: Int): Boolean {
var b: Boolean
do {
a = biased(n)
b = biased(n)
}
while (a == b)
return a
}
fun main(args: Array<String>) {
val m = 50_000
val f = "%d: %2.2f%% %2.2f%%"
for (n in 3..6) {
var c1 = 0
var c2 = 0
for (i in 0 until m) {
if (biased(n)) c1++
if (unbiased(n)) c2++
}
println(f.format(n, 100.0 * c1 / m, 100.0 * c2 / m))
}
}</lang>
Sample output:
<pre>
3: 33.19% 50.19%
4: 25.29% 49.85%
5: 19.91% 50.07%
6: 16.71% 50.14%
</pre>
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