rans_encode

Builtin index · File I/O

result = rans_encode(data)

Input: data · Output: result

What it is

rANS entropy coding of data (a Str, or a Vec of 0-255 byte values) — a static frequency table, unlike range_encode's adaptive model, so the table travels with the payload.

Overloads

One call shape — this function is not overloaded.

Code	Input	Output	Description
`result = rans_encode(data)`	`data` Str or Vecnot documented yet	`freq` Veca length-256 `Vec`, the symbol frequency table `bytes` Veca `Vec` of 0-255 coded bytes `symbol_count` Numa `Num`, the input length	Returns a `Record` with fields `freq` (a length-256 `Vec`, the symbol frequency table), `bytes` (a `Vec` of 0-255 coded bytes) and `symbol_count` (a `Num`, the input length). Empty input gives `none` rather than a record.

Examples

From the documentation, and run by the build -- the output and the figure below are what the engine actually produced. Simplest first.

s = "hello hello hello compression world"
enc = rans_encode(s)
print(numel(enc.bytes))                    # coded length, in bytes

print(rans_decode(enc, as_str = true) == s)  # true

output

18
true

from file-io