{
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  {
   "cell_type": "markdown",
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   "source": [
    "# The Self-Conscious Statisticians"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "9613f11e",
   "metadata": {},
   "source": [
    "Imagine a group of statisticians who are in a weight loss program.  Because they're statisticians, they want to quantify the group's progress, but because they're self-conscious, none want to reveal their weight publicly.  This is a perfect use-case for Cicada and MPC:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "id": "978d8658",
   "metadata": {},
   "outputs": [
    {
     "name": "stderr",
     "output_type": "stream",
     "text": [
      "INFO:root:Sum revealed to player 0: 904.0\n",
      "INFO:root:Sum revealed to player 1: 904.0\n",
      "INFO:root:Sum revealed to player 2: 904.0\n",
      "INFO:root:Sum revealed to player 3: 904.0\n",
      "INFO:root:Sum revealed to player 4: 904.0\n",
      "INFO:root:Mean weight revealed to player 0: 180.7978515625\n",
      "INFO:root:Mean weight revealed to player 1: 180.7978515625\n",
      "INFO:root:Mean weight revealed to player 2: 180.7978515625\n",
      "INFO:root:Mean weight revealed to player 3: 180.7978515625\n",
      "INFO:root:Mean weight revealed to player 4: 180.7978515625\n"
     ]
    }
   ],
   "source": [
    "import logging\n",
    "\n",
    "import numpy\n",
    "\n",
    "from cicada.additive import AdditiveProtocolSuite\n",
    "from cicada.communicator import SocketCommunicator\n",
    "from cicada.logger import Logger\n",
    "\n",
    "logging.basicConfig(level=logging.INFO)\n",
    "\n",
    "def main(communicator):\n",
    "    log = Logger(logging.getLogger(), communicator)\n",
    "    protocol = AdditiveProtocolSuite(communicator)\n",
    "\n",
    "    # Each player loads their weight from a file.\n",
    "    weight = numpy.loadtxt(f\"statistician-weight-{communicator.rank}.txt\")\n",
    "        \n",
    "    # Compute the sum of the player weights.\n",
    "    sum_share = protocol.share(src=0, secret=numpy.array(0), shape=())\n",
    "    for rank in communicator.ranks:\n",
    "        weight_share = protocol.share(src=rank, secret=weight, shape=())\n",
    "        sum_share = protocol.add(sum_share, weight_share)\n",
    "        \n",
    "    # Divide by the number of players to obtain the mean weight.\n",
    "    count_share = protocol.share(src=0, secret=numpy.array(communicator.world_size), shape=())\n",
    "    mean_share = protocol.divide(sum_share, count_share)\n",
    "                                 \n",
    "    # Reveal the total and average weight to the group.\n",
    "    sum = protocol.reveal(sum_share)\n",
    "    mean = protocol.reveal(mean_share)\n",
    "                                 \n",
    "    log.info(f\"Sum revealed to player {communicator.rank}: {sum}\")\n",
    "    log.info(f\"Mean weight revealed to player {communicator.rank}: {mean}\")\n",
    "    \n",
    "SocketCommunicator.run(world_size=5, fn=main);"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "fe32e50b",
   "metadata": {},
   "source": [
    "If we manually inspect the players' weights, we can see that the result is correct, making allowances for the default 16-bit fixed point precision:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "id": "4c04a1bb",
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Player 0 weight: 130.0\n",
      "Player 1 weight: 220.0\n",
      "Player 2 weight: 98.0\n",
      "Player 3 weight: 241.0\n",
      "Player 4 weight: 215.0\n",
      "sum: 904.0\n",
      "mean: 180.8\n"
     ]
    }
   ],
   "source": [
    "weights = [numpy.loadtxt(f\"statistician-weight-{rank}.txt\") for rank in range(5)]\n",
    "\n",
    "for rank, weight in enumerate(weights):\n",
    "    print(f\"Player {rank} weight: {weight}\")\n",
    "\n",
    "print(f\"sum: {numpy.sum(weights)}\")\n",
    "print(f\"mean: {numpy.mean(weights)}\")"
   ]
  }
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