{
  "cells": [
    {
      "cell_type": "markdown",
      "metadata": {},
      "source": [
        "# Variables, Values, Types, Strings, and Dates\n",
        "\n**Opening question:** How does Python know whether a value is a price, a label, a date, or a logical condition?\n"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "metadata": {},
      "outputs": [],
      "source": [
        "country = \"Canada\"\n",
        "policy_rate = 0.0275\n",
        "observations = 120\n",
        "is_monthly = True\n",
        "\n",
        "print(type(policy_rate).__name__)\n",
        "print(f\"{country}: {policy_rate:.2%}, n={observations}, monthly={is_monthly}\")\n"
      ]
    },
    {
      "cell_type": "markdown",
      "metadata": {},
      "source": [
        "**Interpretation check:** Interpretation. The format specification changes presentation, not the stored value.\n"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "metadata": {},
      "outputs": [],
      "source": [
        "from datetime import date\n",
        "\n",
        "start = date.fromisoformat(\"2026-01-01\")\n",
        "end = date.fromisoformat(\"2026-08-15\")\n",
        "print((end - start).days)\n",
        "print(start < end)\n"
      ]
    },
    {
      "cell_type": "markdown",
      "metadata": {},
      "source": [
        "**Interpretation check:** Interpretation. ISO dates avoid day-month ambiguity and support calendar arithmetic.\n"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "metadata": {},
      "outputs": [],
      "source": [
        "print(type(policy_rate).__name__)\n",
        "print(f\"{country}: {policy_rate:.2%}, n={observations}, monthly={is_monthly}\")\n",
        "from datetime import date\n",
        "start = date.fromisoformat(\"2026-01-01\")\n",
        "end = date.fromisoformat(\"2026-08-15\")\n",
        "print((end - start).days)\n"
      ]
    },
    {
      "cell_type": "markdown",
      "metadata": {},
      "source": [
        "## Verified source output\n",
        "\n",
        "```text\nfloat Canada: 2.75%, n=120, monthly=True\n```\n\n```text\n226 True\n```\n\n```text\nfloat\nCanada: 2.75%, n=120, monthly=True\n```\n\n```text\n226\nTrue\n```\n"
      ]
    }
  ],
  "metadata": {
    "kernelspec": {
      "display_name": "Python 3",
      "language": "python",
      "name": "python3"
    },
    "language_info": {
      "name": "python",
      "version": "3"
    },
    "ceteris_lab": {
      "course_slug": "fundamentals-python-econometrics",
      "source_derived": true,
      "course_title": "Fundamentals of Python for Financial Econometrics",
      "chapter": 3,
      "source_origin": "source-derived"
    }
  },
  "nbformat": 4,
  "nbformat_minor": 5
}