RunLength

Versión 1.2.0.0 (18.7 KB) por Jan
RunLength coding as fast MEX and M-code
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Actualizado 8 Apr 2017

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RUNLENGTH - Run-length coding
Run-length encoding splits a vector into one vector, which contains the
elements without neighboring repetitions, and a second vector, which
contains the number of repetitions.
This can reduce the memory for storing the data or allow to analyze sequences.
Encoding: [B, N, BI] = RunLength(X)
Decoding: X = RunLength(B, N)
INPUT / OUTPUT:
X: Full input signal, row or column vector.
Types: (U)INT8/16/32/64, SINGLE, DOUBLE, LOGICAL, CHAR.
B: Compressed data, neighboring elements with the same value are removed.
B and X have the same types.
N: Number of repetitions of the elements of B in X as DOUBLE or UINT8 row vector.
BI: Indices of elements in B in X as DOUBLE row vector.
RunLength(X, 'byte') replies N as UINT8 vector.

You can find a lot of RLE tools in the FileExchange already. This C-Mex is
about 5 times faster than good vectorized M-versions.
The M-file RunLength_M contains vectorized and loop M-code for education.

EXAMPLES:
Encode and decode:
[b, n] = RunLength([8, 9, 9, 10, 10, 10, 11])
x = RunLength(b, n)
% b = [8,9,10,11], n = [1,2,3,1], x = [8,9,9,10,10,10,11]
Limit counter to 255:
[b, n] = RunLength(ones(1, 257), 'byte')
% b = [1, 1], n = uint8([255, 2])
LOGICAL input:
[b, n] = RunLength([true(257, 1); false])
% b = [true; false], n = [257, 1]
Find the longest sequence:
x = floor(rand(1, 1e6) * 2);
[b, n, bi] = RunLength(x);
[longestRun, index] = max(n);
longestPos = bi(index);

The C-code is compiled automatically the first time RunLength is called.
See "RunLength_ReadMe.txt" for more details.

The unit-test uTest_RunLength tests validity and speed.

Tested: Matlab 6.5, 7.7, 7.8, 7.13, WinXP/32, Win7/64
Compiler: LCC3.8, BCC5.5, OWC1.8, MSVC2008/2010
Does not compile under LCC2.4 shipped with Matlab/32!
Assumed Compatibility: higher Matlab versions, Linux, MacOS.

Citar como

Jan (2024). RunLength (https://www.mathworks.com/matlabcentral/fileexchange/41813-runlength), MATLAB Central File Exchange. Recuperado .

Compatibilidad con la versión de MATLAB
Se creó con R2011b
Compatible con cualquier versión
Compatibilidad con las plataformas
Windows macOS Linux
Categorías
Más información sobre Large Files and Big Data en Help Center y MATLAB Answers.
Agradecimientos

Inspiración para: runindex, FillGaps_ez

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Versión Publicado Notas de la versión
1.2.0.0

2nd output is a column vector also, when the input is one. Thanks The Cyclist.

1.1.0.0

In the former submission the file RunLength.inc was missing. ReadMe added.

1.0.0.0