{
 "cells": [
  {
   "cell_type": "markdown",
   "id": "16b134de-8c9f-4c21-8ef9-8d4121fb7c67",
   "metadata": {},
   "source": [
    "\n",
    "### Preallocating arrays vs push in julia"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "10827d90-8f2b-4064-b6c7-c8553c851b37",
   "metadata": {},
   "outputs": [],
   "source": [
    "] add BenchmarkTools"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "a71fc89d-fece-4758-9c26-d2be649d928b",
   "metadata": {},
   "outputs": [],
   "source": [
    "\n",
    "using BenchmarkTools"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "612d79ec-6ec7-4eea-b8bd-dc8136e59ddb",
   "metadata": {},
   "source": [
    "\n",
    "Allocate array of a fixed length and store the elements as they are calculated"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "c94681aa-b8f8-4c6c-8095-3972c566458e",
   "metadata": {},
   "outputs": [],
   "source": [
    "\n",
    "function init1(n)\n",
    "    x = zeros(n)\n",
    "    for i = 1:n\n",
    "        x[i] = i/2\n",
    "    end\n",
    "    return x\n",
    "end"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "08e0dd34-fbfc-4afe-89c4-b43a2867c294",
   "metadata": {},
   "source": [
    "\n",
    "Create a zero-length array and expand it as new element need to be stored"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "e772ceb6-6b16-4c05-ab3d-064d1e47ee71",
   "metadata": {},
   "outputs": [],
   "source": [
    "\n",
    "function init2(n)\n",
    "    x = []\n",
    "    for i = 1:n\n",
    "        push!(x, i/2)\n",
    "    end\n",
    "    return x\n",
    "end"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "f8b8d84e-3ba8-40a3-a8be-3494d79bbc83",
   "metadata": {},
   "outputs": [],
   "source": [
    "\n",
    "x1 = init1(100)\n",
    "x2 = init2(100);"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "7ce6efe4-25e0-4be2-80fe-5e6ba1bdccbd",
   "metadata": {},
   "outputs": [],
   "source": [
    "\n",
    "\n",
    "x1 == x2"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "88c606c3-9f0d-4bcc-931c-51bfa132e96f",
   "metadata": {},
   "outputs": [],
   "source": [
    "\n",
    "@btime init1(100);"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "1838e095-128c-468a-b643-59ede475d8ba",
   "metadata": {},
   "outputs": [],
   "source": [
    "\n",
    "@btime init2(100);"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "4feff9b3-6c4a-4141-8ffd-e6b81434f0fe",
   "metadata": {},
   "outputs": [],
   "source": []
  }
 ],
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  "kernelspec": {
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   "file_extension": ".jl",
   "mimetype": "application/julia",
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