Decimal Module
The AE technique encodes the entire message, regardless of its length, into a single floating-point number.
In Python, the float data type is restricted to a limited number of decimal digits.
A Python float cannot accurately save a number beyond this number of decimal digits.
The exact number of digits is returned using the dig attribute in the str.
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Encoding
Encoding in AE works by representing the cumulative probabilities of all symbols on a line that ranges from 0.0 to 1.0.
On that line, each symbol uses a sub-range.
Given any symbol C, it starts from the value Sand ends at the value calculated using the following equation: S+(P(C))*R Where:.
1) S: The cumulative sum of all previous probabilities. 2. .
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Frequency Table
To encode (= compress) a message using AE, you need these inputs:.
1) The message you want to encode..
2) The frequency table of all possible symbols in the message.
The frequency table is usually calculated by analyzing different messages and concluding by the number of times each symbol is repeated.
For example: assume that the messages to be encod.
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How to compress and decompress a 7z file in Python?
Code example.
To compress and decompress .7z files you need to use py7zr component.
Code example.
In your daily work, in addition to using Python to process text files, sometimes you will also be involved in processing compressed files.
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Is there an efficient way to compress data in Python?
However, Python offers several different ways to compress data.
Is there one of these that's particularly efficient for pickled files.
The data I'm pickling mostly consists of nested dictionaries and strings, so if there's a more efficient way to compress e.g.
JSON, that would work too.
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Overview of The Lossless Algorithm
In data compression, lossy algorithms compress data while losing some details.
They reduce the number of bits used to represent the message, even if that reduces the quality of reconstructed data.
Lossless algorithms reconstruct original data without any loss.
Because of this, they use a higher number of bits compared to lossy algorithms.
Arithmeti.
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Probability Table
Using the frequency table, we can calculate the probability of occurrence of each symbol.
The probability is calculated as follows: Frequency of a symbol/Sum of frequencies of all symbols Based on the frequency table, here are the probabilities of our 3 symbols: 1. p(a)=2/10=0.2 2. p(b)=7/10=0.7 3. p(c)=1/10=0.1 Given the message and the probabilit.
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What is DEFLATE compression in Python?
is a library and that provides code for working with Deflate compression and decompression format which is used by and many others.
So, by using this Python module, you're essentially using compatible compression algorithm without the convenient wrapper.
More about this library can be found on compression.
