Your 'model.py' ABM1 code should look something like the following:
import random
import math
# Set the pseudo-random seed for reproducibility
random.seed(0)
# Initialise variable x0
x0 = random.randint(0, 99)
print("x0", x0)
# Initialise variable y0
y0 = random.randint(0, 99)
print("y0", y0)
# Change x0 and y0 randomly
rn = random.random()
print("rn", rn)
if rn < 0.5:
x0 = x0 + 1
else:
x0 = x0 - 1
print("x0", x0)
rn = random.random()
print("rn", rn)
if rn < 0.5:
y0 = y0 + 1
else:
y0 = y0 - 1
print("y0", y0)
# Initialise variable x1
x1 = random.randint(0, 99)
print("x1", x1)
# Initialise variable y1
y1 = random.randint(0, 99)
print("y1", y1)
# Change x1 and y1 randomly
rn = random.random()
print("rn", rn)
if rn < 0.5:
x1 = x1 + 1
else:
x1 = x1 - 1
print("x1", x1)
rn = random.random()
print("rn", rn)
if rn < 0.5:
y1 = y1 + 1
else:
y1 = y1 - 1
print("y1", y1)
# Calculate the Euclidean distance between (x0, y0) and (x1, y1)
# Set x0 and y0 to equal 0, x1 to equal 3, and y1 to equal 4
x0 = 0
y0 = 0
x1 = 3
y1 = 4
# Calculate the difference in the x coordinates.
dx = x0 - x1
# Calculate the difference in the y coordinates.
dy = y0 - y1
# Square the differences and add the squares
ssd = (dx * dx) + (dy * dy)
print("ssd", ssd)
# Calculate the square root
distance = ssd ** 0.5
print("distance", distance)
distance = math.sqrt(ssd)
print("distance", distance)Running the code should produce the following text output:
x0 49 y0 97 rn 0.890243920837131 x0 48 rn 0.04048437818077755 y0 98 x1 65 y1 62 rn 0.4049341374504143 x1 66 rn 0.7837985890347726 y1 61 ssd 25 distance 5.0 distance 5.0
In your local code repository src directory create a new directory called 'abm2'. Open Spyder and save 'model.py' into the 'abm2' directory.
Rather than handle coordinates for each agent individually, the coordinates for each agent are now going to be stored inlists of length 2, with the first item being an 'x' coordinate, and the second item being a 'y' cordinate. All agents are also going to be stored in a list.
The code is also going to be reorganised so that the agents are created in a for loop, and there will be a second for loop to adjust the coordinates (move the agents).
Towards the top of the file (below the import statements and setting of the random seed) add the following to create a new empty list called 'agents':
# Create a list to store agents
agents = []Next, add coordinates to this list: First add one pair after initialising 'y0' and 'x0', by adding the following:
agents.append([x0,y0]) # Append to the list agentsNote that '[x0,y0]' creates a list containing 'x0' and 'y0', and the 'append' function adds this list to the agents list. After doing this, 'agents[0][0]' is the 'x' coordinate of the first agent in the agents list and 'agents[0][1]' is the 'y' coordinate of the first agent in the agents list.
Go through and replace all the other uses of 'x0' with indexed list references, i.e. 'agents[0][0]' and 'y0' with 'agents[0][1]' (uses - not the initial assignments). Check your code still runs.
The code that creates the first agent and adds this to the agents list should be as follows:
# Initialise variable x0
x0 = random.randint(0, 99)
print("x0", x0)
# Initialise variable y0
y0 = random.randint(0, 99)
print("y0", y0)
agents.append([x0, y0])Note that the variables 'x0' and 'y0' are only created for this initialisation. Can you think of a way to reduce this code and do the initialition more succinctly?
To plot the agents using Matplotlib add the following import statements:
import matplotlib.pyplot as plt
import operatorAnd adding the following code to the end of 'model.py':
# Plot the agents
plt.scatter(agents[0][0], agents[0][1], color='black')
plt.scatter(agents[1][0], agents[1][1], color='black')
plt.show()
# Get the coordinates with the largest x-coordinate
print(max(agents, key=operator.itemgetter(0)))Run 'model.py' and you should see an image output in the 'Plots' pane of Spyder. The image should contain two points.
Have a look at the matplotlib pyplot documentation
After the code that plots the points black, plot the point with the largest x coordinate red. One way to do this is to store those coordinates in a variable and then pass the x-coordinate and y-coordinate as arguments to the command aliased as 'plt' before the 'show()' command.
Have a try and don't worry if you don't get this to work.
This section guides you through restructuring your code so that agent initialisation (for all agents) happens first, and moving (for all agents) happens second. There will be loops for each of these things and for plotting all the agents.
To prepare yourself, review your code. In doing so, it might help to insert some blank lines to separate different parts of it, and to add more comments to help you understand what it is doing. Once you have done that, commit your code to your local repository and assuming you are using GitHub - push your changes to GitHub.
Comment out the code for initialising and changing the coordinates of the second agent. After the line of code that initialises the agent list add a variable called 'n_agents' and set this equal to '10'. Then create a for loop that uses n_agents to create 10 agents. The code you want is:
n_agents = 10
for i in range(n_agents):
agents.append([random.randint(0, 99), random.randint(0, 99)])Check that your program still runs.
You no longer want any code that initialises other agents.
Use another for loop to move all 10 agents. And use another for loop to plot all 10 agents black. Hopefully, there is still a red coloured dot which gives the location of the agent with the largest x coordinate.
Add and commit to your local git repository and assuming you are using GitHub - push your changes to GitHub.
Similarly to plotting the agent with the largest x coordinate red, write code to plot the agent with the smallest x coordinate blue; the largest y coordinate yellow; and the smallest y coordinate green.
Commit your code to your local repository and assuming you are using GitHub - push your changes to GitHub.
If you managed to complete all parts, then it should be straight forward to modify your code to run for different numbers of agent. Have a try and also think about how you would get the agents to move multiple times.
If you got stuck, then don't worry, look ahead to the start of the next ABM practical where some code that does everything is provided.
Next we will look in more detail about functions and how to document them. Then in the next ABM practical: a loop will be created to simulate movement of the agents multiple times; and the distance calculation code, which is currently just a test case, will be changed into a function. Most of the next practical will be an exercise involving calculating the maximum distance between agents and timing code to optimise this.