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Entropy (view source)

Revision as of 05:18, 14 January 2022

4,541 bytes added ,  2 years ago
m
→‎{{header|Phix}}: log2 now a builtin, added syntax colouring, marked p2js compatible
(→‎{{header|Wren}}: Now uses new core library method.)
m (→‎{{header|Phix}}: log2 now a builtin, added syntax colouring, marked p2js compatible)
Line 2,044:
 
=={{header|Phix}}==
<!--<lang Phix>function log2(atom vphixonline)-->
<span style="color: #008080;">with</span> <span style="color: #008080;">javascript_semantics</span>
return log(v)/log(2)
<span style="color: #008080;">function</span> <span style="color: #000000;">entropy</span><span style="color: #0000FF;">(</span><span style="color: #004080;">sequence</span> <span style="color: #000000;">s</span><span style="color: #0000FF;">)</span>
end function
<span style="color: #004080;">sequence</span> <span style="color: #000000;">symbols</span> <span style="color: #0000FF;">=</span> <span style="color: #0000FF;">{},</span>
 
<span style="color: #000000;">counts</span> <span style="color: #0000FF;">=</span> <span style="color: #0000FF;">{}</span>
function entropy(sequence s)
<span style="color: #004080;">integer</span> <span style="color: #000000;">N</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">length</span><span style="color: #0000FF;">(</span><span style="color: #000000;">s</span><span style="color: #0000FF;">)</span>
sequence symbols = {},
<span style="color: #008080;">for</span> <span style="color: #000000;">i</span><span style="color: #0000FF;">=</span><span style="color: #000000;">1</span> <span style="color: #008080;">to</span> <span style="color: #000000;">N</span> <span style="color: #008080;">do</span>
counts = {}
<span style="color: #004080;">object</span> <span style="color: #000000;">si</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">s</span><span style="color: #0000FF;">[</span><span style="color: #000000;">i</span><span style="color: #0000FF;">]</span>
integer N = length(s)
<span style="color: #004080;">integer</span> <span style="color: #000000;">k</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">find</span><span style="color: #0000FF;">(</span><span style="color: #000000;">si</span><span style="color: #0000FF;">,</span><span style="color: #000000;">symbols</span><span style="color: #0000FF;">)</span>
for i=1 to N do
<span style="color: #008080;">if</span> <span style="color: #000000;">k</span><span style="color: #0000FF;">=</span><span style="color: #000000;">0</span> <span style="color: #008080;">then</span>
object si = s[i]
<span style="color: #000000;">symbols</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">append</span><span style="color: #0000FF;">(</span><span style="color: #000000;">symbols</span><span style="color: #0000FF;">,</span><span style="color: #000000;">si</span><span style="color: #0000FF;">)</span>
integer k = find(si,symbols)
<span style="color: #000000;">counts</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">append</span><span style="color: #0000FF;">(</span><span style="color: #000000;">counts</span><span style="color: #0000FF;">,</span><span style="color: #000000;">1</span><span style="color: #0000FF;">)</span>
if k=0 then
<span symbols style="color: append(symbols,si)#008080;">else</span>
<span style="color: #000000;">counts</span><span style="color: #0000FF;">[</span><span style="color: #000000;">k</span><span style="color: #0000FF;">]</span> <span style="color: #0000FF;">+=</span> <span style="color: #000000;">1</span>
counts = append(counts,1)
<span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
else
<span style="color: #008080;">end</span> <span style="color: #008080;">for</span>
counts[k] += 1
<span style="color: #004080;">atom</span> <span style="color: #000000;">H</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">0</span>
end if
<span style="color: #004080;">integer</span> <span style="color: #000000;">n</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">length</span><span style="color: #0000FF;">(</span><span style="color: #000000;">counts</span><span style="color: #0000FF;">)</span>
end for
<span style="color: #008080;">for</span> <span style="color: #000000;">i</span><span style="color: #0000FF;">=</span><span style="color: #000000;">1</span> <span style="color: #008080;">to</span> <span style="color: #000000;">n</span> <span style="color: #008080;">do</span>
atom H = 0
<span style="color: #004080;">atom</span> <span style="color: #000000;">ci</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">counts</span><span style="color: #0000FF;">[</span><span style="color: #000000;">i</span><span style="color: #0000FF;">]/</span><span style="color: #000000;">N</span>
integer n = length(counts)
<span style="color: #000000;">H</span> <span style="color: #0000FF;">-=</span> <span style="color: #000000;">ci</span><span style="color: #0000FF;">*</span><span style="color: #7060A8;">log2</span><span style="color: #0000FF;">(</span><span style="color: #000000;">ci</span><span style="color: #0000FF;">)</span>
for i=1 to n do
<span style="color: #008080;">end</span> <span style="color: #008080;">for</span>
atom ci = counts[i]/N
<span style="color: #008080;">return</span> <span style="color: #000000;">H</span>
H -= ci*log2(ci)
<span style="color: #008080;">end</span> <span style="color: #008080;">function</span>
end for
return H
<span style="color: #0000FF;">?</span><span style="color: #000000;">entropy</span><span style="color: #0000FF;">(</span><span style="color: #008000;">"1223334444"</span><span style="color: #0000FF;">)</span>
end function
<!--</lang>-->
 
?entropy("1223334444")</lang>
{{out}}
<pre>
Petelomax
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