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We are working towards making exercises stand-alone. That is to say: no more generating READMEs on the fly. This will give maintainers more control over each individual exercise README, and it will also make some of the backend logic for delivering exercises simpler. The README template uses the Go text/template package, and the default templates generate the same READMEs as we have been generating on the fly. See the documentation in [regenerating exercise readmes][regenerate-docs] for details. The READMEs can be generated at any time using a new 'generate' command in configlet. This command has not yet landed in master or been released, but can be built from source in the generate-readmes branch on [configlet][]. [configlet]: https://github.com/exercism/configlet [regenerate-docs]: https://github.com/exercism/docs/blob/master/maintaining-a-track/regenerating-exercise-readmes.md
72 lines
2.3 KiB
Markdown
72 lines
2.3 KiB
Markdown
# Hamming
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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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## Elm Installation
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Refer to the [Exercism help page](http://exercism.io/languages/elm) for Elm
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installation and learning resources.
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## Writing the Code
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The first time you start an exercise, you'll need to ensure you have the
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appropriate dependencies installed.
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```bash
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$ npm install
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```
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Execute the tests with:
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```bash
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$ npm test
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```
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Automatically run tests again when you save changes:
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```bash
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$ npm run watch
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```
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As you work your way through the test suite, be sure to remove the `skip <|`
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calls from each test until you get them all passing!
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## Source
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The Calculating Point Mutations problem at Rosalind [http://rosalind.info/problems/hamm/](http://rosalind.info/problems/hamm/)
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## Submitting Incomplete Solutions
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It's possible to submit an incomplete solution so you can see how others have completed the exercise.
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