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# Questions tagged [compression]

Data compression is a process used to reduce the number of bits used to store a "message". Compression can be lossless or lossy. Lossy compression is an option for audio and visual data, whereas many other applications require lossless compression.

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### Is feature-extraction and dimensionality-reduction a kind of compression?

I'm struggling to understand what these terms have in common: Feature extraction Feature selection Compression Dimensionality reduction Relatedly, the information / entropy in our data should always ...
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### Removing minimally informative bits

Each sample in my data set is an $N$-bit bit-vector (say $N$=200). The bits in each sample are not uncorreleated within the sample. I built a matrix $S_{N \times N}$ with each $s_{ij}$ being the ...
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### Analyzing 3D data: What can be done?

I am new to this kind of analysis, and I want to know what values I can look at in 3D data. The data itself is a 3D volume $(x,y,z)$ with a floating point value in every coordinate. It is a ...
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### Comparison of entropy and distribution of bytes in compressed/encrypted data

I have some question which occupies myself for a while. The entropy test is often used to identify encrypted data. The entropy reaches its maximum when the bytes of the analyzed data are distributed ...
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2 votes
1 answer
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### Distance independent approximation of Nearest Neighbor/k-NN.

Nearest neighbor/k-NN for use with Normalized Compression Distance. I wonder if there exist any approximation of NN/k-NN algorithm which work for all distance measures ? I would like to test ...
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### Dense Data Compression (Delta Encoding?)

Let $X$ be a dense integer set such that its elements are closely knit in value. For instance: 1 1 1 1 2 2 2 2 2 3 3 5 5 6 6 6 6 6 7 7 7 7 8 8 8 8 8 8 ... I am ...
4 votes
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### Weights of random sets of random 32-bit strings

I have random sets of $N$ random 32-bit strings, where all bits are i.i.d. with $\mathbb{P}(0) = \mathbb{P}(1) = 1/2$. Define $\ \ \ \$weight( 32-bit x ) = number of 1 bits in x, i.e. Hamming ...
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### How to compress sets of integer series?

I have a set of integer series $S_1$, $S_2$, ... $S_n$. Each series has 3600 data points. Each data point is a positive integer. Each data point is stored as an ...
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4 votes
4 answers
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### Ultimate compression algorithm

I was not sure where to put this question, so I put it here. Feel free to move it to another stack exchange site moderators. Lets say I have a 10 gigs of pictures (or for that matter any type of data,...
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### Compression theory, practice, for time series with values in a space of distributions (say of a real random variable)

Example of problem: Part of our research team is working on providing operationally wind power forecast. Usually, since there are different time scalse that interest forecast user, a forecast is ...
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### How to compute theoretical compression limit?

Assume we have a sensor field with dimension M*M. In order to apply any data compression technique, first I want to know what is the compression limit or minimum entropy of the entire sensor field. ...
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