Python 3.9 on MBA M1: hash of functions, vs elif

elif.ipynb

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   "source": [
    "## Is it better to write \"elif\" or use a hash of functions?\n",
    "\n",
    "\n",
    "On a MacBook Air M1, the crossover point is 7. If you have 7 or more elif arms, consider switching to a hash of functions.\n",
    "\n",
    "|N|hash|elif|\n",
    "|----|----|----|\n",
    "|5|89.3|77.8|\n",
    "|7|88|88.8|\n",
    "|10|87.3|107|\n",
    "\n",
    "The numbers below are a fresh run."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "id": "magnetic-system",
   "metadata": {},
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    "N = 7\n",
    "fs = {}\n",
    "res = 0"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "novel-extraction",
   "metadata": {},
   "source": [
    "Functions `function0`..`functionN` are created, which all set a global variable. They are injected into the `fs[]` hash."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "id": "private-harvest",
   "metadata": {},
   "outputs": [],
   "source": [
    "for i in range(N):\n",
    "    exec(f\"def function{i}(): res = '{i}'\")\n",
    "    exec(f\"fs[{i}] = function{i}\")"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "quality-hearts",
   "metadata": {},
   "source": [
    "Produce some cut&pasteable code for timeit."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "id": "medical-birth",
   "metadata": {},
   "outputs": [],
   "source": [
    "def big_elseif(n, indent):\n",
    "    s = indent\n",
    "    for i in range(n):\n",
    "        s = s + f\"\"\"if x == {i}: res= '{i}'\\n{indent}el\"\"\"\n",
    "    s = s + \"se: raise\"\n",
    "    return s"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "id": "north-gospel",
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "if x == 0: res= '0'\n",
      "elif x == 1: res= '1'\n",
      "elif x == 2: res= '2'\n",
      "elif x == 3: res= '3'\n",
      "elif x == 4: res= '4'\n",
      "elif x == 5: res= '5'\n",
      "elif x == 6: res= '6'\n",
      "else: raise\n"
     ]
    }
   ],
   "source": [
    "print(big_elseif(N, \"\"))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "id": "governmental-reputation",
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "91.8 ns ± 0.748 ns per loop (mean ± std. dev. of 7 runs, 10000000 loops each)\n"
     ]
    }
   ],
   "source": [
    "%%timeit x=0\n",
    "x = (x + 1) % N\n",
    "f = fs[x]\n",
    "f()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 6,
   "id": "living-holiday",
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "90.7 ns ± 0.603 ns per loop (mean ± std. dev. of 7 runs, 10000000 loops each)\n"
     ]
    }
   ],
   "source": [
    "%%timeit x=0\n",
    "x = (x + 1) % N\n",
    "if x == 0: res= '0'\n",
    "elif x == 1: res= '1'\n",
    "elif x == 2: res= '2'\n",
    "elif x == 3: res= '3'\n",
    "elif x == 4: res= '4'\n",
    "elif x == 5: res= '5'\n",
    "elif x == 6: res= '6'\n",
    "else: raise"
   ]
  }
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