Homework 4: Plan Composition

Due Tuesday Novmber 23 11:59pm via InstructAssist.

This assignment builds on this week’s material on different ways to structure solutions to the same problem.

For each of the following problems, write two solutions, where each solution solves the problem using a different approach. Approaches count as different if they cluster at least some subtasks of the problems differently (like we saw for the Rainfall solutions); more syntactic differences, such as replacing an element-based for-loop with an index-based one, don’t count as different.

You should also determine which of your solution structures you prefer. As part of submitting the assignment, fill out this form with your preferences and a brief discussion of why.

Please download and use this set of starter classes. The starter files contain all the classes and interfaces needed for this assignment, as well as the classes in which to put your answers (to aid us in grading). You may add whatever methods you wish to these classes, but please don’t rename any classes, fields, or methods. The section below on Using the Starter Files explains the starter files and where you should edit them with your solutions.

1 Programming Problems

A personal health record (PHR) contains four pieces of information on a patient: their name, height (in meters), weight (in kilograms), and last recorded heart rate (as beats-per-minute). A doctor’s office maintains a list of the personal health records of all its patients.

Several problems will refer to these PHRs. The starter files contain a class for PHRs.

1.1 The BMI Sorter

Body mass index (BMI) is a measure that attempts to quantify an individual’s tissue mass. It is commonly collected during annual checkups or clinic visits. It is defined as:

BMI = weight / ( height * height )

A simplified BMI scale classifies a value below 18.5 as “underweight”, a value at least 18.5 but under 25 as “healthy”, a value at least 25 but under 30 as “overweight”, and a value at least 30 as “obese”.

Design a program called bmiReport that consumes a list of personal health records (defined above) and produces a report containing a list of names (not the entire records) of patients in each BMI classification category. The names can be in any order. Use the BMISummary class in the starter files for the report:

1.2 Data Smoothing

In data analysis, smoothing a data set means approximating it to capture important patterns in the data while eliding noise or other fine-scale structures and phenomena. One simple smoothing technique is to replace each (internal) element of a sequence of values with the average of that element and its predecessor and successor. Assuming that extreme outlier values are an abberation caused, perhaps, through poor measurement, this averaging process replaces them with a more plausible value in the context of that sequence.

For example, consider this sequence of heartRate values taken from a list of personal health records (defined above):

95 102 98 88 105

The resulting smoothed sequence should be

95 98.33 96 97 105

where:

102 was substituted by 98.33: (95 + 102 + 98) / 3
98 was substituted by 96: (102 + 98 + 88) / 3
88 was substituted by 97: (98 + 88 + 105) / 3

This information can be plotted in a graph such as below, with the smoothed graph superimposed over the original values.

Design a program dataSmooth that consumes a list of PHRs and produces a list of the smoothed heartRate values (not the entire records).

1.3 Most Frequent Words

Given a list of strings, design a program frequentWords that produces a list containing the three strings that occur most frequently in the input list. The output list should contain the most frequent word first, followed by the second most frequent, then the third most frequent. Break ties by putting the shorter word (by length in characters) first. You may assume that the three most frequent words will have different lengths. You may also assume that the input will have at least three different words.

1.4 Earthquake Monitoring

Geologists want to monitor a local mountain for potential earthquake activity. They have installed a sensor to track seismic (vibration of the earth) activity. The sensor sends measurements one at a time over the network to a computer at a research lab. The sensor inserts markers among the measurements to indicate the date of the measurement. The sequence of values coming from the sensor looks as follows:

20151004 200 150 175 20151005 0.002 0.03 20151007 ...

The 8-digit numbers are dates (in year-month-day format). Numbers between 0 and 500 are vibration frequencies (in Hz). This example shows readings of 200, 150, and 175 on October 4th, 2015 and readings of 0.002 and 0.03 on October 5th, 2015. There are no data for October 6th (sometimes there are problems with the network, so data go missing). Assume that the data are in order by dates (so a later date never appears before an earlier one in the sequence) and that all data are from the same year [the latter assumption was added/clarified on 11/19].

[Clarification added 11/22] You may also assume that every date is followed by at least one frequency (in other words, every date has at least one datum).

Design a program dailyMaxForMonth that consumes a list of sensor data (doubles) and a month (represented by a number between 1 and 12) and produces a list of reports indicating the highest frequency reading for each day in that month. Only include entries for dates that are part of the data provided (so don’t report anything for October 6th in the example shown). Ignore data for months other than the given one. Each entry in your report should be an instance of the maxHzReport class in the starter files.

2 Using the Starter Files

The starter files zip has a lot of files. Here’s a guide to what you will find in there.

For each problem, there are at least four files:

Files named <Problem>1.java and <Problem>2.java. Put one of your solutions in each of these files. The headers are already there, but the methods currently return null so that things will compile. Replace the method bodies with your methods.
A file named <Problem>Examples.java. Your test cases and data for the problem go in here, as usual. The constructors in these classes take arguments (not usual for our Examples classes). We’ve set this up this way so that you can write one set of test cases and have it run automatically on each of your two solutions.
Each Examples class has a dummy test case in it that has the right structure (extracting your method from an object that implements the problem). These also use null to get stuff to compile, but you should replace that with real test cases once you start working. Our custom Main.java file is written to run all of the tests in your Examples class on each of your solutions. You can comment lines out of the Main.java file if you only want to test one of your solutions at a given time.
An interface file that you should not need to edit.
Auxiliary files with the classes for reports, PHRs, etc

Please post to the forum if you need help understanding the files. We set these up in advance to (a) help autograding, and (b) save you from having to do this setup yourselves.

3 Submission Guidelines

Edit the starter files, then zip them up and submit that zip to InstructAssist. There is a separate Examples class for each problem, which will assist us in autograding. Each method in your Examples classes should test only the single method for that problem.

Remember to fill in this form with your ranking preferences, too!

1	Programming Problems
2	Using the Starter Files
3	Submission Guidelines