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   "source": [
    "## Writing GRIB to a file target"
   ]
  },
  {
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   "execution_count": 1,
   "id": "b7db8543-3a37-4eaf-8729-261f46e3ca18",
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      "text/plain": [
       "test.grib:   0%|          | 0.00/1.03k [00:00<?, ?B/s]"
      ]
     },
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     "output_type": "display_data"
    }
   ],
   "source": [
    "# get input GRIB data\n",
    "import earthkit.data as ekd\n",
    "ds = ekd.from_source(\"sample\", \"test.grib\")"
   ]
  },
  {
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   "source": [
    "#### Using to_target() on the data object"
   ]
  },
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   "source": [
    "We use :func:`to_target` to write the GRIB fieldlist/field into a file. The encoder is automatically guessed from the input data."
   ]
  },
  {
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   "id": "01d115db-17f0-456a-afc5-ea81367d18b5",
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   "source": [
    "# writing a field\n",
    "ds[0].to_target(\"file\", \"_res_t.grib\")\n",
    "\n",
    "# writing a whole fieldlist\n",
    "ds.to_target(\"file\", \"_res_t.grib\")"
   ]
  },
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    "# setting GRIB keys for the output\n",
    "ds.to_target(\"file\", \"_res_t.grib\", metadata={\"date\": 20250108}, bitsPerValue=8)\n",
    "\n",
    "ekd.from_source(\"file\", \"_res_t.grib\").ls(extra_keys=[\"bitsPerValue\"])"
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   "source": [
    "# data can be appended to the output file\n",
    "ds[1].to_target(\"file\", \"_res_t.grib\")\n",
    "ds[0].to_target(\"file\", \"_res_t.grib\", append=True)\n",
    "ekd.from_source(\"file\", \"_res_t.grib\").ls(extra_keys=[\"bitsPerValue\"])"
   ]
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  {
   "cell_type": "markdown",
   "id": "211ac929-3464-4165-a2a3-d8fb4903a7e3",
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   "source": [
    "#### Using a Target object"
   ]
  },
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   "source": [
    "We can create a target object with :func:`get_target` and use :meth:`write` to write/add data to it."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "id": "47cef925-6caf-4cee-bec0-e4467db510f0",
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   "source": [
    "# basic usage\n",
    "target = ekd.create_target(\"file\", \"_res_t.grib\")\n",
    "target.write(ds)\n",
    "target.close()\n",
    "\n",
    "# can be used as a context manager, no need to call close() in the end\n",
    "with ekd.create_target(\"file\", \"_res_t.grib\") as target:\n",
    "    target.write(ds)\n",
    "\n",
    "# a filedlist can be written field by field into the target\n",
    "with ekd.create_target(\"file\", \"_res_t.grib\") as target:\n",
    "    for f in ds:\n",
    "        target.write(f)"
   ]
  },
  {
   "cell_type": "markdown",
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   "source": [
    "#### Using encoders"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "2aa6644d-1c90-4550-a88f-af2ee0d6b909",
   "metadata": {
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   "source": [
    "These calls are equivalent."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 6,
   "id": "a86840f7-4b99-4ab6-911d-60726d771a31",
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   "source": [
    "# setting metadata and other GRIB keys for the output\n",
    "ds.to_target(\"file\", \"_res_t.grib\", metadata={\"date\": 20250108}, bitsPerValue=8)\n",
    "\n",
    "# explicitly specifying the encoder\n",
    "ds.to_target(\"file\", \"_res_t.grib\", encoder=\"grib\", metadata={\"date\": 20250108}, bitsPerValue=8)\n",
    "\n",
    "# using an encoder object\n",
    "encoder = ekd.create_encoder(\"grib\", metadata={\"date\": 20250108})\n",
    "ds.to_target(\"file\", \"_res_t.grib\", encoder=encoder,  bitsPerValue=8)"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "176b71c1-9830-4f4e-af75-6857467308bb",
   "metadata": {
    "editable": true,
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    },
    "tags": []
   },
   "source": [
    "The same can be done with a target object."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 7,
   "id": "310476ce-9d73-4624-a933-2df468586a23",
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   "outputs": [],
   "source": [
    "encoder = ekd.create_encoder(\"grib\", metadata={\"date\": 20250108})\n",
    "with ekd.create_target(\"file\", \"_res_t.grib\") as target:\n",
    "    target.write(ds, encoder=encoder,  bitsPerValue=8)"
   ]
  }
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