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    ".. _slicing:\n",
    "\n",
    "Slicing\n",
    "=======\n",
    "\n",
    "Recall from the :ref:`tutorial` that in Cicada, *secrets* are always arrays that could have zero, one, or many dimensions. Consequently *secret shares* are also multidimensional arrays, supporting similar array manipulation functions. Chief among these is *slicing*, which returns a secret share referencing a subset of the original array.\n",
    "\n",
    "For example, you could compute the sum of a range of values from a 1D array:"
   ]
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     "output_type": "stream",
     "text": [
      "INFO:root:Player 0 sum: 45.0\n",
      "INFO:root:Player 1 sum: 45.0\n",
      "INFO:root:Player 2 sum: 45.0\n",
      "INFO:root:Player 0 subset sum: 9.0\n",
      "INFO:root:Player 1 subset sum: 9.0\n",
      "INFO:root:Player 2 subset sum: 9.0\n"
     ]
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   "source": [
    "import logging\n",
    "\n",
    "import numpy\n",
    "\n",
    "from cicada.active import ActiveProtocolSuite\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 = ActiveProtocolSuite(communicator, threshold=2)\n",
    "\n",
    "    secret = numpy.arange(10) if communicator.rank == 0 else None\n",
    "    share = protocol.share(src=0, secret=secret, shape=(10,))\n",
    "\n",
    "    # Sum every value in the array.\n",
    "    log.info(f\"Player {communicator.rank} sum: {protocol.reveal(protocol.sum(share))}\")\n",
    "\n",
    "    # Sum the 2nd, 3rd, and 4th values in the array.\n",
    "    log.info(f\"Player {communicator.rank} subset sum: {protocol.reveal(protocol.sum(share[2:5]))}\")\n",
    "\n",
    "SocketCommunicator.run(world_size=3, fn=main, show_traceback=True)"
   ]
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   "source": [
    "In fact Cicada supports all of the indexing operations supported by :doc:`numpy:user/basics.indexing`. For example, you could sum just the odd-numbered elements in an array:"
   ]
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     "text": [
      "INFO:root:Player 0 sum: 45.0\n",
      "INFO:root:Player 1 sum: 45.0\n",
      "INFO:root:Player 2 sum: 45.0\n",
      "INFO:root:Player 0 subset sum: 25.0\n",
      "INFO:root:Player 1 subset sum: 25.0\n",
      "INFO:root:Player 2 subset sum: 25.0\n"
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   "source": [
    "def main(communicator):\n",
    "    log = Logger(logging.getLogger(), communicator)\n",
    "    protocol = ActiveProtocolSuite(communicator, threshold=2)\n",
    "\n",
    "    secret = numpy.arange(10) if communicator.rank == 0 else None\n",
    "    share = protocol.share(src=0, secret=secret, shape=(10,))\n",
    "\n",
    "    # Sum every value in the array.\n",
    "    log.info(f\"Player {communicator.rank} sum: {protocol.reveal(protocol.sum(share))}\")\n",
    "\n",
    "    # Sum the odd numbered elements in the array.\n",
    "    log.info(f\"Player {communicator.rank} subset sum: {protocol.reveal(protocol.sum(share[1::2]))}\")\n",
    "\n",
    "SocketCommunicator.run(world_size=3, fn=main, show_traceback=True)"
   ]
  }
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