add plot range

python/population_plot.py

@@ -1,25 +1,35 @@
 import matplotlib.pyplot as plt
 import numpy as np
 
-# Initial population
-population = 1_000_000
+# Initial population at year 1
+initial_population = 1_000_000
 death_rate = 0.10
-years = np.arange(4000, 10001, 500)  # 4000 to 10000 years in 500-year intervals
 
-# Calculate population after each 500-year interval
+# Start and stop years for the graph
+start_year = 4000
+stop_year = 10000
+interval = 500  # Interval for plotting data points
+
+# Calculate the population at the start of the start_year
+current_population = initial_population
+for _ in range(start_year // 100):  # Dividing by 100 as the death rate is applied every 100 years
+    current_population -= death_rate * current_population
+
+# Now calculate and plot the population from start_year to stop_year
+years = np.arange(start_year, stop_year + 1, interval)
 population_values = []
 for year in years:
-    # Apply the death rate for each 500-year period (5 times for each interval)
-    for _ in range(5):
-        population -= death_rate * population
-    population_values.append(population)
+    # Apply the death rate for each interval (interval/100 times for each period)
+    for _ in range(interval // 100):
+        current_population -= death_rate * current_population
+    population_values.append(current_population)
 
 # Create the graph with labels for each data point
 plt.figure(figsize=(8, 6))
 plt.plot(years, population_values, marker='o', linestyle='-', color='b')
 plt.xlabel('Years')
 plt.ylabel('Population')
-plt.title('Population Projection from Year 4000')
+plt.title(f'Population Projection from Year {start_year} to {stop_year}')
 
 # Adding labels to the data points
 for i, txt in enumerate(population_values):