intro tutorial: Explain how to plot reporter of multiple agents

This is a section taken from #1717.

Co-authored-by: Ewout ter Hoeven <[email protected]>

docs/tutorials/intro_tutorial.ipynb

@@ -1059,6 +1059,60 @@
     "g.set(title=\"Wealth of agent 14 over time\");"
    ]
   },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "You can also plot a reporter of multiple agents over time."
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "agent_list = [3, 14, 25]\n",
+    "\n",
+    "# Get the wealth of multiple agents over time\n",
+    "multiple_agents_wealth = agent_wealth[\n",
+    "    agent_wealth.index.get_level_values(\"AgentID\").isin(agent_list)\n",
+    "]\n",
+    "# Plot the wealth of multiple agents over time\n",
+    "g = sns.lineplot(data=multiple_agents_wealth, x=\"Step\", y=\"Wealth\", hue=\"AgentID\")\n",
+    "g.set(title=\"Wealth of agents 3, 14 and 25 over time\");"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "We can also plot the average of all agents, with a 95% confidence interval for that average."
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "# Transform the data to a long format\n",
+    "agent_wealth_long = agent_wealth.T.unstack().reset_index()\n",
+    "agent_wealth_long.columns = [\"Step\", \"AgentID\", \"Variable\", \"Value\"]\n",
+    "agent_wealth_long.head(3)\n",
+    "\n",
+    "# Plot the average wealth over time\n",
+    "g = sns.lineplot(data=agent_wealth_long, x=\"Step\", y=\"Value\", errorbar=(\"ci\", 95))\n",
+    "g.set(title=\"Average wealth over time\")"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "Which is exactly 1, as expected in this model, since each agent starts with one wealth unit, and each agent gives one wealth unit to another agent at each step."
+   ]
+  },
   {
    "cell_type": "markdown",
    "metadata": {},
@@ -1369,7 +1423,7 @@
  "metadata": {
   "anaconda-cloud": {},
   "kernelspec": {
-   "display_name": "Python 3",
+   "display_name": "Python 3 (ipykernel)",
    "language": "python",
    "name": "python3"
   },
@@ -1383,7 +1437,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython3",
-   "version": "3.9.6"
+   "version": "3.10.12"
   },
   "widgets": {
    "state": {},