Files used in 'Raspberry Pi & Python basic data storage with Tony D!' live stream.

00_none.py

# Python Data Storage Demos Example 0: No Data Storage
# Basic setup for demos which show different ways to store program state (data)
# using standard and other Python libraries.  This example has no data storage
# and will always show default values when run.
#
# Author: Tony DiCola
# License: Public Domain


# Create a class to represent a person and their favorite color.
class Person(object):

    def __init__(self):
        # Set name and favorite color to defaults.
        self.name = 'No Name'
        self.favorite_color = 'Black'

    def load(self):
        # Attempt to load the person state from some file/storage system.
        # For now this is unimplemented!
        pass

    def save(self):
        # Attempt to save the person state to a file/storage system.
        # For now this is unimplemented!
        pass


# Main program which creates a person and prompts with a menu to change their
# name or favorite color.
if __name__ == '__main__':
    # Create a person instance and try to load any previous state.
    person = Person()
    person.load()
    # Now run in a loop and allow the name and color to be changed.
    while True:
        # Print out a menu of options.
        print('Hello {0}! Your favorite color is: {1}'.format(person.name, person.favorite_color))
        print('Options:')
        print(' 1 - Change name')
        print(' 2 - Change favorite color')
        print(' 3 - Quit')
        option = input('Enter option: ')
        # Check that the selected option is valid.
        if option not in ('1', '2', '3'):
            # Print an error and go back to the start of the loop.
            print('Unknown option!')
            continue
        if option == '1':
            # Change person's name.
            person.name = input('New name: ')
        elif option == '2':
            # Change person's favorite color:
            person.favorite_color = input('Favorite color: ')
        elif option == '3':
            # Break out of the loop to exit.
            print('Goodbye!')
            break
    # Once the main loop ends (by picking the quit option) save the person state.
    person.save()

01_pickle.py

# Python Data Storage Demos Example 1: Pickle Module
# Persist a person object to disk using Python's pickle module for Python object
# persistence.
#
# Author: Tony DiCola
# License: Public Domain
import pickle


# Create a class to represent a person and their favorite color.
class Person(object):

    def __init__(self):
        # Set name and favorite color to defaults.
        self.name = 'No Name'
        self.favorite_color = 'Black'

    def load(self):
        # Attempt to load the person state from a person.pickle file.
        try:
            with open('person.pickle', 'rb') as person_file:
                # Use pickle.load to convert the file data into a python object.
                person = pickle.load(person_file)
                # Now copy out the name and favorite color to this object instance.
                self.name = person.name
                self.favorite_color = person.favorite_color
        except FileNotFoundError:
            # Ignore file not found error, the default person class will be used.
            pass

    def save(self):
        # Attempt to save the person state to a person.pickle file.
        with open('person.pickle', 'wb') as person_file:
            pickle.dump(self, person_file)


# Main program which creates a person and prompts with a menu to change their
# name or favorite color.
if __name__ == '__main__':
    # Create a person instance and try to load any previous state.
    person = Person()
    person.load()
    # Now run in a loop and allow the name and color to be changed.
    while True:
        # Print out a menu of options.
        print('Hello {0}! Your favorite color is: {1}'.format(person.name, person.favorite_color))
        print('Options:')
        print(' 1 - Change name')
        print(' 2 - Change favorite color')
        print(' 3 - Quit')
        option = input('Enter option: ')
        # Check that the selected option is valid.
        if option not in ('1', '2', '3'):
            # Print an error and go back to the start of the loop.
            print('Unknown option!')
            continue
        if option == '1':
            # Change person's name.
            person.name = input('New name: ')
        elif option == '2':
            # Change person's favorite color:
            person.favorite_color = input('Favorite color: ')
        elif option == '3':
            # Break out of the loop to exit.
            print('Goodbye!')
            break
    # Once the main loop ends (by picking the quit option) save the person state.
    person.save()

02_configparser.py

# Python Data Storage Demos Example 2: configparser Module
# Persist a person object to disk using Python's configparser module that reads
# and writes .ini style configuration files.
#
# Author: Tony DiCola
# License: Public Domain
import configparser


# Create a class to represent a person and their favorite color.
class Person(object):

    def __init__(self):
        # Set name and favorite color to defaults.
        self.name = 'No Name'
        self.favorite_color = 'Black'

    def load(self):
        # Attempt to load the person state from a person.ini file.
        try:
            with open('person.ini', 'r') as person_file:
                # Read the file with configparser
                config = configparser.ConfigParser()
                config.read_file(person_file)
                # Now grab the name and favorite color as attributes from the
                # 'Person' section of the config file.
                self.name = config['Person']['name']
                self.favorite_color = config['Person']['favorite_color']
        except FileNotFoundError:
            # Ignore file not found error, defaults will be used instead.
            pass

    def save(self):
        # Attempt to save the person state to a person.ini file.
        with open('person.ini', 'w') as person_file:
            config = configparser.ConfigParser()
            config['Person'] = { 'name': self.name,
                                 'favorite_color': self.favorite_color }
            config.write(person_file)


# Main program which creates a person and prompts with a menu to change their
# name or favorite color.
if __name__ == '__main__':
    # Create a person instance and try to load any previous state.
    person = Person()
    person.load()
    # Now run in a loop and allow the name and color to be changed.
    while True:
        # Print out a menu of options.
        print('Hello {0}! Your favorite color is: {1}'.format(person.name, person.favorite_color))
        print('Options:')
        print(' 1 - Change name')
        print(' 2 - Change favorite color')
        print(' 3 - Quit')
        option = input('Enter option: ')
        # Check that the selected option is valid.
        if option not in ('1', '2', '3'):
            # Print an error and go back to the start of the loop.
            print('Unknown option!')
            continue
        if option == '1':
            # Change person's name.
            person.name = input('New name: ')
        elif option == '2':
            # Change person's favorite color:
            person.favorite_color = input('Favorite color: ')
        elif option == '3':
            # Break out of the loop to exit.
            print('Goodbye!')
            break
    # Once the main loop ends (by picking the quit option) save the person state.
    person.save()

03_timeseries_csv.py

# Python Data Storage Demos Example 3: CSV for time-series data
# Persist sensor readings over time to a CSV (comma-separated file).  This is
# great for easily storing time-series data in a file that can be read by
# other programs (like graphing in a spreadsheet).
#
# Author: Tony DiCola
# License: Public Domain
import csv
import datetime
import random
import time


# Create a new sensor.csv file that will contain a set of randomly generated
# fake sensor readings.
with open('sensor.csv', 'w') as csv_file:
    writer = csv.writer(csv_file)
    # Write a header row with the name of each column.
    writer.writerow(['Time', 'Humidity (%)', 'Temperature (F)'])
    # Now loop generating new fake sensor readings every second and writing them
    # to the CSV file.
    while True:
        # Make some fake sensor data.
        reading_time = datetime.datetime.now()
        humidity = random.uniform(0, 100)
        temperature = random.uniform(-32, 120)
        # Print out the data and write to the CSV file.
        print('Time: {0} Humidity: {1} Temperature: {2}'.format(reading_time, humidity, temperature))
        writer.writerow([reading_time, humidity, temperature])
        # Pause for a second and repeat.
        time.sleep(1)