Search results
Results from the WOW.Com Content Network
A dictionary coder, also sometimes known as a substitution coder, is a class of lossless data compression algorithms which operate by searching for matches between the text to be compressed and a set of strings contained in a data structure (called the 'dictionary') maintained by the encoder. When the encoder finds such a match, it substitutes ...
The move-to-front (MTF) transform is an encoding of data (typically a stream of bytes) designed to improve the performance of entropy encoding techniques of compression.When efficiently implemented, it is fast enough that its benefits usually justify including it as an extra step in data compression algorithm.
Examples: An empty string is encoded as 0:. The string "bencode" is encoded as 7:bencode. Lists are encoded as l<elements>e. Begins with l and ends with e. Elements are bencoded values concatenated without delimiters. Examples: An empty list is encoded as le. A list containing the string "bencode" and the integer -20 is encoded as l7:bencodei-20ee.
For example, one could define a dictionary having a string "toast" mapped to the integer 42 or vice versa. The keys in a dictionary must be of an immutable Python type, such as an integer or a string, because under the hood they are implemented via a hash function. This makes for much faster lookup times, but requires keys not change.
Incremental encoding is widely used in information retrieval to compress the lexicons used in search indexes; these list all the words found in all the documents and a pointer for each one to a list of locations. Typically, it compresses these indexes by about 40%.
^ Omitted XML elements are commonly decoded by XML data binding tools as NULLs. Shown here is another possible encoding; XML schema does not define an encoding for this datatype. ^ The RFC CSV specification only deals with delimiters, newlines, and quote characters; it does not directly deal with serializing programming data structures.
Typical 2G standards include GSM and IS-95 with extensions via GPRS, EDGE and 1xRTT, providing Internet access to users of originally voice centric 2G networks. Both EDGE and 1xRTT are 3G standards, as defined by the ITU , but are usually marketed as 2.9G due to their comparatively low speeds and high delays when compared to true 3G technologies.
2G, or second-generation cellular network technology, marks the transition from analog to digital communication in mobile networks. Defined by the European Telecommunications Standards Institute (ETSI) under the GSM standard, which became the first globally adopted framework for mobile communications, 2G was first commercially launched in 1991 by Radiolinja (now part of Elisa Oyj) in Finland. [1]