{
  "cells": [
    {
      "cell_type": "markdown",
      "metadata": {},
      "source": [
        "\n# Customising Xarray Dataset\n"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "metadata": {
        "collapsed": false
      },
      "outputs": [],
      "source": [
        "from datetime import datetime, timedelta\nimport xarray as xr\nfrom opendrift import test_data_folder as tdf\nfrom opendrift.readers import reader_netCDF_CF_generic\nfrom opendrift.models.oceandrift import OceanDrift\n\no = OceanDrift(loglevel=20)  # Set loglevel to 0 for debug information"
      ]
    },
    {
      "cell_type": "markdown",
      "metadata": {},
      "source": [
        "Opening the currents netCDF file with xarray\n\n"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "metadata": {
        "collapsed": false
      },
      "outputs": [],
      "source": [
        "ds = xr.open_dataset(tdf + '16Nov2015_NorKyst_z_surface/norkyst800_subset_16Nov2015.nc')"
      ]
    },
    {
      "cell_type": "markdown",
      "metadata": {},
      "source": [
        "Creating and adding a landmask DataArray (variable) based on the u-current component\n\n"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "metadata": {
        "collapsed": false
      },
      "outputs": [],
      "source": [
        "ds['landmask'] = ds.u.isel(time=0).isel(depth=0) * 0  # 0 (ocean) where current is finite\nds['landmask'] = ds.landmask.fillna(1)  # 1 (land) where current is NaN\nds['landmask'] = ds.landmask.assign_attrs(standard_name='land_binary_mask')  # Adding attribute standard_name so that this variable is recognised as landmask"
      ]
    },
    {
      "cell_type": "markdown",
      "metadata": {},
      "source": [
        "Creating an OpenDrift reader from this modified xarray dataset, and confirming that landmask is recognised\n\n"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "metadata": {
        "collapsed": false
      },
      "outputs": [],
      "source": [
        "r = reader_netCDF_CF_generic.Reader(ds)\nprint(r)\no.add_reader(r)\n\no.set_config('general:use_auto_landmask', False)  # Disable the automatic GSHHG landmask, so that the custom landmask is used"
      ]
    },
    {
      "cell_type": "markdown",
      "metadata": {},
      "source": [
        "Seeding a particle and running simulation, and confirming that the custom landmask is used for stranding\n\n"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "metadata": {
        "collapsed": false
      },
      "outputs": [],
      "source": [
        "o.seed_elements(lon=4.9, lat=60.0, time=r.start_time)\no.run(end_time=r.end_time)\no.plot(fast=True)"
      ]
    }
  ],
  "metadata": {
    "kernelspec": {
      "display_name": "Python 3",
      "language": "python",
      "name": "python3"
    },
    "language_info": {
      "codemirror_mode": {
        "name": "ipython",
        "version": 3
      },
      "file_extension": ".py",
      "mimetype": "text/x-python",
      "name": "python",
      "nbconvert_exporter": "python",
      "pygments_lexer": "ipython3",
      "version": "3.14.2"
    }
  },
  "nbformat": 4,
  "nbformat_minor": 0
}