SCC212 Javascript

Task 1: Frequency Counts

You’ve been asked to produce the counts of particular sequences handed to you from a test framework. The framework itself has a function for you to call with the results.

In essence, if you have been given the following sequence of nucleotide letters:

CCAAATT

We should be able to generate the following counts of each pattern in the following structure:

{ AA: 2, AT: 1, CC: 1, CA: 1, TT: 1 }

Note that ‘AA’ is detected as two patterns, as the first pair of ‘A’s then a second pair of overlapping ‘A’s:

CC AA ATT and CCA AA TT

Your code will be handed the input character-by-character, so it will be up to you how you decide to buffer and detect these sequences.

In the supplied .zip file, you should have 6 data files (in pairs, for each task), and two JavaScript files. One is the library you are to use (testlib.js) and the other is a template to base your implementation on (minimal_demo.js). You should not modify testlib.js . All need to be in the same folder to operate correctly.

To run the demo file, execute ‘node minimal_demo.js’ from the command line or terminal in the program’s folder.

The minimal_demo includes how to connect to the testlib library, along with how to start the test. The source code of the library is documented on the functions available for your use.

For this particular task, you are required to use the testlib.frequencyTable() function to report your frequency counts. This function expects that you supply it with an object containing keys as specified by the patterns array in the ‘ready’ handler, each with a count of the number of times the program has seen that pattern.

Remember that you can access JavaScript object and array keys by square brackets.

An (extremely simple) example of how to do this might be:

Note: To know when one sequence stops and another begins, use the ‘reset’ hook via the testlib.on() function