fix range and

python/population_plot.py

@@ -1,7 +1,7 @@
 import matplotlib.pyplot as plt
 import numpy as np
 
-# Initial population at year 1
+# Initial population at year 0
 initial_population = 1_000_000
 death_rate = 0.10
 
@@ -10,30 +10,30 @@ start_year = 4000
 stop_year = 10000
 interval = 500  # Interval for plotting data points
 
-# Calculate the population at the start of the start_year
+# Initialize population calculations
 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
+population_values = [initial_population]  # Include initial population as the first data point
+years = np.arange(0, stop_year + 1, 100)  # Calculate every 100 years
 
-# 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 interval (interval/100 times for each period)
-    for _ in range(interval // 100):
+# Apply the death rate for each 100-year period
+for year in years[1:]:
     current_population -= death_rate * current_population
     population_values.append(current_population)
 
+# Filter the years and population values for the graph
+graph_years = np.arange(start_year, stop_year + 1, interval)
+graph_population_values = [population for year, population in zip(years, population_values) if year >= start_year and year in graph_years]
+
 # 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.plot(graph_years, graph_population_values, marker='o', linestyle='-', color='b')
 plt.xlabel('Years')
 plt.ylabel('Population')
 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):
-    plt.annotate(f"{int(txt):,}", (years[i], population_values[i]), textcoords="offset points", xytext=(0,10), ha='center')
+for i, txt in enumerate(graph_population_values):
+    plt.annotate(f"{int(txt):,}", (graph_years[i], graph_population_values[i]), textcoords="offset points", xytext=(0,10), ha='center')
 
 plt.grid(True)
 plt.show()