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   "source": [
    "# Setting specific lags\n",
    "\n",
    "Example created by Wilson Rocha Lacerda Junior"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Different ways to set the maximum lag for input and output"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "pip install sysidentpy"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {},
   "outputs": [],
   "source": [
    "import numpy as np\n",
    "import pandas as pd\n",
    "import matplotlib.pyplot as plt\n",
    "from sysidentpy.model_structure_selection import FROLS\n",
    "from sysidentpy.basis_function._basis_function import Polynomial\n",
    "from sysidentpy.metrics import root_relative_squared_error\n",
    "from sysidentpy.utils.generate_data import get_siso_data\n",
    "from sysidentpy.utils.display_results import results\n",
    "from sysidentpy.utils.plotting import plot_residues_correlation, plot_results\n",
    "from sysidentpy.residues.residues_correlation import compute_residues_autocorrelation, compute_cross_correlation\n"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Setting lags using a range of values\n",
    "\n",
    "If you pass int values for *ylag* and *xlag*, the lags are defined as a range from 1-*ylag* and 1-*xlag*. \n",
    "\n",
    "For example: if *ylag=4* then the candidate regressors are $y_{k-1}, y_{k-2}, y_{k-3}, y_{k-4}$"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {
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   "outputs": [],
   "source": [
    "basis_function = Polynomial(degree=1)\n",
    "\n",
    "model = FROLS(\n",
    "    order_selection=True,\n",
    "    extended_least_squares=False,\n",
    "    ylag=4, xlag=4,\n",
    "    info_criteria='aic',\n",
    "    estimator='least_squares',\n",
    "    basis_function=basis_function\n",
    ")"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Setting specific lags using lists\n",
    "\n",
    "If you pass the *ylag* and *xlag* as a list, only the lags related to values in the list will be created."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "metadata": {},
   "outputs": [],
   "source": [
    "model = FROLS(\n",
    "    order_selection=True,\n",
    "    extended_least_squares=False,\n",
    "    ylag=[1, 4], xlag=[1, 4],\n",
    "    info_criteria='aic',\n",
    "    estimator='least_squares',\n",
    "    basis_function=basis_function\n",
    ")"
   ]
  }
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