Run-length encoding Replacing a long series of a repeated character with a count of the repe-tition 68 Chapter 3 Data Representation (because they appear in many different words). A disadvantage, as before, is that they are generally short patterns and the replacement savings per word is small. Run-Length Encoding In some situations, a single character may be repeated over and over again in a long sequence. This type of repetition doesn’t generally take place in English text, but often occurs in large data streams, such as DNA sequences. A text compression technique called run-length encoding capi-talizes on these situations. Run-length encoding is sometimes called recur-rence coding . In run-length encoding, a sequence of repeated characters is replaced by a flag character , followed by the repeated character, followed by a single digit that indicates how many times the character is repeated. For example, consider the following string of seven repeated ‘A’ characters: AAAAAAA
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