60 lines
2.0 KiB
Markdown
60 lines
2.0 KiB
Markdown
# Hamming
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Write a program that can calculate the Hamming difference between two DNA strands.
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A mutation is simply a mistake that occurs during the creation or
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copying of a nucleic acid, in particular DNA. Because nucleic acids are
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vital to cellular functions, mutations tend to cause a ripple effect
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throughout the cell. Although mutations are technically mistakes, a very
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rare mutation may equip the cell with a beneficial attribute. In fact,
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the macro effects of evolution are attributable by the accumulated
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result of beneficial microscopic mutations over many generations.
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The simplest and most common type of nucleic acid mutation is a point
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mutation, which replaces one base with another at a single nucleotide.
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By counting the number of differences between two homologous DNA strands
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taken from different genomes with a common ancestor, we get a measure of
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the minimum number of point mutations that could have occurred on the
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evolutionary path between the two strands.
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This is called the 'Hamming distance'.
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It is found by comparing two DNA strands and counting how many of the
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nucleotides are different from their equivalent in the other string.
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GAGCCTACTAACGGGAT
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CATCGTAATGACGGCCT
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^ ^ ^ ^ ^ ^^
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The Hamming distance between these two DNA strands is 7.
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# Implementation notes
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The Hamming distance is only defined for sequences of equal length. This means
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that based on the definition, each language could deal with getting sequences
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of equal length differently.
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## Setup
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Go through the setup instructions for PL/SQL to get ready to code:
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http://help.exercism.io/getting-started-with-plsql.html
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## Running the Tests
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Execute the tests by calling the `run` method in the respective `ut_<exercise>#` package.
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The necessary code should be contained at the end of the test package.
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As an example, the test for the _hamming_ exercise would be run using
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```
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begin
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ut_hamming#.run;
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end;
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/
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```
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## Source
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The Calculating Point Mutations problem at Rosalind [view source](http://rosalind.info/problems/hamm/)
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