Arithmetic coding/As a generalized change of radix: Difference between revisions

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m (→‎{{header|Phix}}: added syntax colouring the hard way, mpz_get_si() => mpz_get_integer().)
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Verify the implementation by decoding the results back into strings and checking for equality with the given strings.
Verify the implementation by decoding the results back into strings and checking for equality with the given strings.

=={{header|11l}}==
{{trans|Python}}

<lang 11l>F cumulative_freq(freq)
[Int = Int] cf
V total = 0
L(b) 256
I b C freq
cf[b] = total
total += freq[b]
R cf

F arithmethic_coding(bytes, radix)

DefaultDict[Int, Int] freq
L(b) bytes
freq[b.code]++

V cf = cumulative_freq(freq)

BigInt base = bytes.len

BigInt lower = 0

BigInt pf = 1

L(b) bytes
lower = lower * base + cf[b.code] * pf
pf *= freq[b.code]

V upper = lower + pf

BigInt power = 0
L
pf I/= radix
I pf == 0
L.break
power++

V enc = (upper - 1) I/ BigInt(radix) ^ power
R (enc, power, freq)

F arithmethic_decoding(=enc, radix, =power, freq)

enc *= radix ^ power

V base = sum(freq.values())

V cf = cumulative_freq(freq)

[Int = Int] dict
L(k, v) cf
dict[v] = k

Int? lchar
L(i) 0 .< base
I i C dict
lchar = dict[i]
E I lchar != N
dict[i] = lchar

V decoded = ‘’
L(i) (base - 1 .< -1).step(-1)
power = BigInt(base) ^ i
V div = enc I/ power

V c = dict[Int(div)]
V fv = freq[c]
V cv = cf[c]

V rem = (enc - power * cv) I/ fv

enc = rem
decoded ‘’= Char(code' c)

R decoded

V radix = 10

L(str) ‘DABDDB DABDDBBDDBA ABRACADABRA TOBEORNOTTOBEORTOBEORNOT’.split(‘ ’)
V (enc, power, freq) = arithmethic_coding(str, radix)
V dec = arithmethic_decoding(enc, radix, power, freq)

print(‘#<25=> #19 * #.^#.’.format(str, enc, radix, power))

I str != dec
X RuntimeError("\tHowever that is incorrect!")</lang>

{{out}}
<pre>
DABDDB => 251 * 10^2
DABDDBBDDBA => 167351 * 10^6
ABRACADABRA => 7954170 * 10^4
TOBEORNOTTOBEORTOBEORNOT => 1150764267498783364 * 10^15
</pre>


=={{header|C sharp|C#}}==
=={{header|C sharp|C#}}==
Retrieved from "https://rosettacode.org/wiki/Arithmetic_coding/As_a_generalized_change_of_radix"