{
 "cells": [
  {
   "cell_type": "markdown",
   "id": "cell-000",
   "metadata": {},
   "source": [
    "# Module 8 (Part A) — Your First Python Project\n",
    "\n",
    "**Companion notebook** for the Module 8A slides. Save it as\n",
    "`notebooks/01_hello.ipynb` in your `actuarial_intro` project and choose the project's\n",
    "`.venv` kernel.\n",
    "\n",
    "Run each cell with **Shift + Enter**. Cells marked **Your turn** have `...` for you to\n",
    "replace; the `check()` cells print ✅ or ❌."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "cell-001",
   "metadata": {},
   "outputs": [],
   "source": [
    "def check(label, got, expected, tol=1e-6):\n",
    "    \"\"\"Compare your answer with the expected value; prints ✅ or ❌ (never raises).\"\"\"\n",
    "    import math\n",
    "    try:\n",
    "        if isinstance(expected, float) or isinstance(got, float):\n",
    "            ok = math.isclose(float(got), float(expected), rel_tol=tol, abs_tol=tol)\n",
    "        elif isinstance(expected, (list, tuple)) and expected and isinstance(expected[0], str):\n",
    "            ok = list(got) == list(expected)\n",
    "        elif hasattr(expected, \"__len__\") and not isinstance(expected, str):\n",
    "            import numpy as np\n",
    "            ok = np.allclose(np.asarray(got, dtype=float), np.asarray(expected, dtype=float), rtol=tol, atol=tol)\n",
    "        else:\n",
    "            ok = got == expected\n",
    "    except Exception:\n",
    "        ok = False\n",
    "    print((\"✅ \" if ok else \"❌ \") + f\"{label}: got {got!r}, expected {expected!r}\")"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "cell-002",
   "metadata": {},
   "source": [
    "## 1. Output with and without `print()`\n",
    "The **last expression** in a cell is displayed automatically. `print()` works anywhere."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "cell-003",
   "metadata": {},
   "outputs": [],
   "source": [
    "rate = 0.05\n",
    "rate"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "cell-004",
   "metadata": {},
   "outputs": [],
   "source": [
    "print(rate)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "cell-005",
   "metadata": {},
   "outputs": [],
   "source": [
    "rate * 2\n",
    "rate * 3          # only this last value is shown"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "cell-006",
   "metadata": {},
   "outputs": [],
   "source": [
    "x = rate * 100    # an assignment displays nothing"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "cell-007",
   "metadata": {},
   "source": [
    "Computers store decimals in binary, so `0.05 * 3` isn't exactly `0.15`. Round for display:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "cell-008",
   "metadata": {},
   "outputs": [],
   "source": [
    "round(rate * 3, 4)"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "cell-009",
   "metadata": {},
   "source": [
    "## 2. Rich display for tables"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "cell-010",
   "metadata": {},
   "outputs": [],
   "source": [
    "import pandas as pd\n",
    "\n",
    "df = pd.DataFrame({\"age\": [30, 40], \"qx\": [0.0008, 0.0016]})\n",
    "df"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "cell-011",
   "metadata": {},
   "outputs": [],
   "source": [
    "print(df)           # plain text, like a script would print"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "cell-012",
   "metadata": {},
   "outputs": [],
   "source": [
    "display(df.head(1))\n",
    "display(df.describe())"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "cell-013",
   "metadata": {},
   "source": [
    "## 3. Where is \"here\"?\n",
    "A notebook's working directory is the folder it's saved in — usually `notebooks/`.\n",
    "That's why data paths from a notebook start with `..`."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "cell-014",
   "metadata": {},
   "outputs": [],
   "source": [
    "from pathlib import Path\n",
    "\n",
    "Path.cwd()"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "cell-015",
   "metadata": {},
   "source": [
    "---\n",
    "## Your turn\n",
    "\n",
    "1. Create a variable `name` holding your name, and `years_to_exam` holding `0.5`.\n",
    "2. Set `weeks` to the number of weeks until the exam (52 weeks a year).\n",
    "3. Build `greeting` with an f-string: `Hello, <name>! Weeks until exam: <weeks>`."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "cell-016",
   "metadata": {},
   "outputs": [],
   "source": [
    "name = years_to_exam = weeks = greeting = None\n",
    "...  # your code here\n",
    "print(greeting)\n",
    "check(\"weeks until exam\", weeks, 26.0)\n",
    "check(\"greeting starts with Hello\", str(greeting).startswith(\"Hello, \"), True)"
   ]
  }
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