read_null_locs.ipynb

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   "cell_type": "markdown",
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   "source": [
    "# 1. Import Libraries"
   ]
  },
  {
   "cell_type": "code",
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   "source": [
    "import plio \n",
    "from plio.io.io_gdal import GeoDataset\n",
    "\n",
    "import struct\n",
    "import numpy as np"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "6940a457-c675-4863-a976-70d7a7f29234",
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   "source": [
    "# 2. Open image and get locations"
   ]
  },
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     "text": [
      "/Users/krodriguez/miniforge3/envs/plio/lib/python3.12/site-packages/osgeo/gdal.py:312: FutureWarning: Neither gdal.UseExceptions() nor gdal.DontUseExceptions() has been explicitly called. In GDAL 4.0, exceptions will be enabled by default.\n",
      "  warnings.warn(\n"
     ]
    }
   ],
   "source": [
    "arr = GeoDataset(\"M1162613292LE.lev1.cub\").read_array()\n",
    "ISISREALNULL = struct.unpack(\">f\", bytes.fromhex(\"FF7FFFFB\"))[0]\n",
    "null_locs = np.argwhere(arr==ISISREALNULL) + 1 # ISIS uses 1-based indexing"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "3b792b39-e857-4ab4-8455-d0cd5374a4a3",
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   "source": [
    "# 3. Print and write out data"
   ]
  },
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     "text": [
      "number of nulls:  1671168\n",
      "truncated locations: \n",
      "[[    1     1]\n",
      " [    1     2]\n",
      " [    1     3]\n",
      " ...\n",
      " [52224  2530]\n",
      " [52224  2531]\n",
      " [52224  2532]]\n",
      "Saving to: test.txt\n"
     ]
    }
   ],
   "source": [
    "# save as a simple line delimited file\n",
    "filename = \"test.txt\"\n",
    "print(f\"Saving to: {filename}\")\n",
    "np.savetxt(filename, null_locs.astype(int), fmt='%d')\n",
    "\n",
    "print(\"number of nulls: \", len(null_locs))\n",
    "print(\"truncated locations: \")\n",
    "print(null_locs)"
   ]
  },
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