Python dictionaries and working out transport carbon emissions
Some useful links
The links to the YouTube videos, and the GitHub account for this section are below:
All the information in this section has been taken from the next links:
Definition, and creating and accessing dictionary entries
Dictionaries are Python's implementation of a data structure that is more generally known as an associative array. A dictionary consists of a collection of key-value pairs. Each key-value pair maps the key to its associated value.
1. Creating a dictionary
2. Updating an entry
1. Method dictionary.get()
The Python dictionary.get() method provides a convenient way of getting the value of a key from a dictionary without checking ahead of time whether the key exists, and without raising an error.
2. Method dictionary.items()
Dictionary.items() returns a list of tuples containing the key-value pairs in the dictionary. The first item in each tuple is the key, and the second item is the key's value.
1. Looping example 1
2. Looping example 2
Using dictionaries inside our app, and working out transport carbon emissions
In this section, we work out users' transport carbon emissions. In the carbon_app.html file, the users select the type of transport. Then, the user is redirected to the webpage where the user introduces the number of kilometers and the type of fuel (e.g., new_entry_bus.html file, new_entry_car.html file, etcetera). In that webpage, the users introduce the kilometers and the type of fuel by using the form that we have created in the package carbon_app, in the forms.py file. Once that the user has introduced the kilometers and the type of fuel, the carbon emissions are calculated in the routes.py file inside the carbon_app package, and the user is redirected to the your_data.html file.
In this section, we focus on the mathematical model to work out the transport carbon emissions. In the next section, we focus on the query that we make to the database to disclose the carbon emissions in the your_data.html file.
In the package carbon_app, in the routes.py file, we focus on the route new_entry_bus (the procedure for the other means of conveyance is the same).
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We need to import the form that we created in the package carbon_app, in the file forms.py.
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We define the emission factor matrixes.
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We define the form that will be used in the new_entry_bus.html file.
Package carbon_app, routes.py file
@carbon_app.route('/carbon_app/new_entry_bus',
methods=['GET','POST'])
@login_required
def new_entry_bus():
form = BusForm()
if form.validate_on_submit():
kms = form.kms.data
fuel = form.fuel_type.data
transport = 'Bus'
# kms = request.form['kms']
# fuel = request.form['fuel_type']
co2 = float(kms) * efco2[transport][fuel]
ch4 = float(kms) * efch4[transport][fuel]
total = co2+ch4
co2 = float("{:.2f}".format(co2))
ch4 = float("{:.2f}".format(ch4))
total = float("{:.2f}".format(total))
emissions = Transport(kms=kms, transport=transport,
fuel=fuel, co2=co2, ch4=ch4, total=total, author=current_user)
db.session.add(emissions)
db.session.commit()
return redirect(url_for('carbon_app.your_data'))
return render_template('carbon_app/new_entry_bus.html',
title='new entry bus', form=form)
