• Decoding Data App
  • Status
  • Module 5: Analyze Energy Usage Data
    • Local Verification Instructions
    • Task 1: Create EnergyData Class
    • Task 2: Get Energy Data
    • Task 3: Convert Energy Data
    • Task 4: Filter Energy Usage Data Records by Area and Date
    • Task 5: Get Total Energy Usage
    • Task 6: Get Energy Data by Area with sensor_app
    • Task 7: Get Energy Data by Date with sensor_app

Draft.

To test this module locally:

• Open a terminal at the root of the project
• Run the command pytest -k module5

The final data field we analyze is the energy usage. In this module, you will create a EneryData class that will process the energy consumption. Again, we will reuse a lot of the code writting so far.

To start, open the file called energy_info.py in the sensor folder.

At the top of the file, import HouseInfo from the house_info module.

Create a child class called EnergyData that inherits the properties and methods from the HouseInfo class.

Still in the EnergyData class, create two class contants to help us process the energy data.

The first constant is called ENERGY_PER_BULB and has the value of 0.2.

The second contant is called ENERGY_BITS and it is set to the hexadecimal number 0x0F0

create a private method called _convert_data() with two parameters, self, and data. This method will help us convert the temperature data.

In the body of the _convert_area() method, create a variable called recs and set it to an empty list.

Still in the EnergyData class, create a private method called _get_energy() with two parameters, self, and rec. This method will help us extract the energy data information from energy_usage data field.

Note: The rec input parameter is a string. This string represent the energy usage in hexadecimal notation form.

The energy_sage field comes as a 3 hexadecimal number (12 bits) form e.g "0xfef". However, only the middle hex number (bits: 4-7 with index notation) represents the energy usage. In order to extract these bits, we will use bitwise operations

To extract the energy information, three steps are required:

1. Update the value of rec by converting the rec string to an integer using int() constructor passing rec and 16 as the two arguments. Now that you have an integer, you can apply bitwise operations.

2. Isolate the energy bits by "anding" the rec integer with the ENERGY_BITS constant. This operation should clear all the bits from the first and third nibble.

3. Then, right shift the rec variable 4 bits.

Finally, your method should return rec at the very end of the method.

Still in the EnergyData class, create a another private method called _convert_data() with two parameters, self, and data. This method will help us convert the energy data.

In the body of the _convert_area() method, create a variable called recs and set it to an empty list.

On a new line, create a for loop to iterate over data list. Use rec as your iterator variable.

Note: The data input parameter is a list of strings. These strings represent percentages of energy usage in hexadecimal form.

In the body of the for loop, convert the rec string values using the _get_energy private method, then, append them to recs.

Finally, your method should return recs (outside of the for loop, and the very end of the method).

Next, we are going to override get_data_by_area and get_data_by_date methods from the parent class.

At the top of the file, import date and datetime from the datetime module.

This time, when you call the parent get_data_by_area or get_data_by_date methods, use "energy_usage" as the filter value.

The methods should look like this:

def get_data_by_area(self, rec_area=0):
    recs = super().get_data_by_area("energy_usage", rec_area)
    return self._convert_data(recs)

def get_data_by_date(self, rec_date=date.today()):
    recs = super().get_data_by_date("energy_usage", rec_date)
    return self._convert_data(recs)

Next, add another method to the EnergyData class and called it calculate_energy_usage. The method should take two input paremeters, self and data. The purpose of this method is to take a list of energy usage values, calculate the cost per light bulb usage, and return the sum of all the values in the data list.

On a new line in the method, define a variable called total_energy and set sum of all converted values in the data list. To achieve this, call the sum built in function. This function should take a list comprehension as the only argument. The list comprehension should use field as the expression variable. The field variable should be multiply by the ENERGY_PER_BULB constant.

Finally, return the total_energy variable at the end of the method.

Open the sensor_app.py file in the sensor directory. At the top of the file, from the energy_info module, import EnergyData.

At the bottom of the file, create an instance of the EnergyData class, and assign it to a variable named energy_data. Pass data as the input argument to the EnergyData constructor.

Create a variable called recs and set it to the get_data_by_area() method of the particle_data object. The get_data_by_area() method should take rec_area=1 as the only argument.

Next, print the length of the recs list by area.

print("\nHouse Energy sensor records for area 1 = {}".format(len(recs)))

Create a variable called total_energy and set it to the calculate_energy_usage method of the energy_data object passing the data=recs as the only argument.

Next, print each of the total energy usage.

print("\tEnergy Usage: {:2.2} Watts".format(total_energy))

To preview your app, open a terminal at the root of the project and run the following command:

python sensor/sensor_app.py

Sample output does not includes previous tasks:

... # previous output

House Energy sensor records for area 1 = 1000
        Energy Usage: 1.5e+03 Watts

FYI: the app will not validate your print() statements.

Still in the sensor_app file, set the recs variable to the return value of get_data_by_date() method of the energy_data object. The method takes rec_date=test_date as the only argument.

Next, print the test_date using the strftime() passing "%m/%d/%y" as the first argument, and the length of the recs list.

print("House Energy sensor records for date: {} = {}".format( test_date.strftime("%m/%d/%y"), len(recs)))

Create a variable called total_energy and set it to the calculate_energy_usage method of the energy_data object passing the data=recs as the only argument.

Next, print each of the total energy usage.

print("\tEnergy Usage: {:2.2} Watts".format(total_energy))

To preview your app, open a terminal at the root of the project and run the following command:

python sensor/sensor_app.py

Sample output does not includes previous tasks:

... # previous output
House Energy sensor records for area 1 = 1000
        Energy Usage: 1.5e+03 Watts
House Energy sensor records for date: 05/09/20 = 20
        Energy Usage: 1.9e+01 Watts

FYI: the app will not validate your print() statements.