{
 "cells": [
  {
   "cell_type": "markdown",
   "id": "e88537e9-cac0-47a3-bc57-519c6c69a5a1",
   "metadata": {},
   "source": [
    "# %load pres_temp_4D_wr\n",
    "# the Scientific Python netCDF 3 interface\n",
    "# http://dirac.cnrs-orleans.fr/ScientificPython/\n",
    "#from Scientific.IO.NetCDF import NetCDFFile as Dataset\n",
    "# the 'classic' version of the netCDF4 python interface\n",
    "# http://code.google.com/p/netcdf4-python/"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "6c7461e8-454d-4389-8a5a-fc1e2c9fd585",
   "metadata": {},
   "source": [
    "See tutorials at http://unidata.github.io/netcdf4-python/"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "id": "eb009511-7227-41bf-bf92-48d46c831f94",
   "metadata": {},
   "outputs": [],
   "source": [
    "from netCDF4 import Dataset\n",
    "from numpy import arange, dtype # array module from http://numpy.scipy.org"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "617f19a2-5f80-41c9-b550-09d55ac426b9",
   "metadata": {},
   "source": [
    "\"\"\"\n",
    "This is an example program which writes some 4D pressure and\n",
    "temperatures. \n",
    "The companion program pres_temp_4D_rd.py shows how\n",
    "to read the netCDF data file created by this program.\n",
    "\n",
    "This example demonstrates the netCDF Python API.\n",
    "It will work either with the Scientific Python NetCDF version 3 interface\n",
    "(http://dirac.cnrs-orleans.fr/ScientificPython/)\n",
    "of the 'classic' version of the netCDF4 interface. \n",
    "(http://netcdf4-python.googlecode.com/svn/trunk/docs/netCDF4_classic-module.html)\n",
    "To switch from one to another, just comment/uncomment the appropriate\n",
    "import statements at the beginning of this file.\n",
    "\n",
    "Jeff Whitaker <jeffrey.s.whitaker@noaa.gov> 20070202\n",
    "\"\"\""
   ]
  },
  {
   "cell_type": "markdown",
   "id": "96b63ece-e0d3-4ded-a7a0-17605eb72c86",
   "metadata": {},
   "source": [
    "# the netCDF variable will be nrecs x nlevs x nlats x nlons."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "id": "49554709-bf01-49a6-8681-15cbaa76a068",
   "metadata": {},
   "outputs": [],
   "source": [
    "nrecs = 2; nlevs = 2; nlats = 6; nlons = 12"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "1da6a8e1-04a1-4a3a-bf30-897b20293c74",
   "metadata": {},
   "source": [
    "# open a new netCDF file for writing."
   ]
  },
  {
   "cell_type": "markdown",
   "id": "a483d22c-e678-41fa-a6af-08e9d01af7c1",
   "metadata": {},
   "source": [
    "See http://unidata.github.io/netcdf4-python/#creatingopeningclosing-a-netcdf-file"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "id": "c771364c-90f6-4dda-8415-11db9f9e4ff0",
   "metadata": {},
   "outputs": [],
   "source": [
    "ncfile = Dataset('pres_temp_4D.nc','w') "
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "id": "434fcb2c-ddb7-41a9-b72a-1ec97f0cedb9",
   "metadata": {},
   "outputs": [],
   "source": [
    "# latitudes and longitudes of grid"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "54c37795-6416-4b3a-98b0-231451899c56",
   "metadata": {},
   "source": [
    "see https://numpy.org/doc/stable/reference/generated/numpy.arange.html"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 6,
   "id": "a6ea71f2-4538-4539-918c-4d7fa32f99d5",
   "metadata": {
    "tags": []
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "(array([-25., -20., -15., -10.,  -5.,   0.], dtype=float32),\n",
       " array([-125., -120., -115., -110., -105., -100.,  -95.,  -90.,  -85.,\n",
       "         -80.,  -75.,  -70.], dtype=float32))"
      ]
     },
     "execution_count": 6,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "lats_out = -25.0 + 5.0*arange(nlats,dtype='float32')\n",
    "lons_out = -125.0 + 5.0*arange(nlons,dtype='float32')\n",
    "lats_out, lons_out"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 7,
   "id": "eab8f79d-590b-4ec0-9f6c-c03d3cac89b8",
   "metadata": {},
   "outputs": [],
   "source": [
    "# output data."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 8,
   "id": "4a00e3dc-ce5f-4b20-8681-d11d70f6a309",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "(array([[[ 900.,  901.,  902.,  903.,  904.,  905.,  906.,  907.,  908.,\n",
       "           909.,  910.,  911.],\n",
       "         [ 912.,  913.,  914.,  915.,  916.,  917.,  918.,  919.,  920.,\n",
       "           921.,  922.,  923.],\n",
       "         [ 924.,  925.,  926.,  927.,  928.,  929.,  930.,  931.,  932.,\n",
       "           933.,  934.,  935.],\n",
       "         [ 936.,  937.,  938.,  939.,  940.,  941.,  942.,  943.,  944.,\n",
       "           945.,  946.,  947.],\n",
       "         [ 948.,  949.,  950.,  951.,  952.,  953.,  954.,  955.,  956.,\n",
       "           957.,  958.,  959.],\n",
       "         [ 960.,  961.,  962.,  963.,  964.,  965.,  966.,  967.,  968.,\n",
       "           969.,  970.,  971.]],\n",
       " \n",
       "        [[ 972.,  973.,  974.,  975.,  976.,  977.,  978.,  979.,  980.,\n",
       "           981.,  982.,  983.],\n",
       "         [ 984.,  985.,  986.,  987.,  988.,  989.,  990.,  991.,  992.,\n",
       "           993.,  994.,  995.],\n",
       "         [ 996.,  997.,  998.,  999., 1000., 1001., 1002., 1003., 1004.,\n",
       "          1005., 1006., 1007.],\n",
       "         [1008., 1009., 1010., 1011., 1012., 1013., 1014., 1015., 1016.,\n",
       "          1017., 1018., 1019.],\n",
       "         [1020., 1021., 1022., 1023., 1024., 1025., 1026., 1027., 1028.,\n",
       "          1029., 1030., 1031.],\n",
       "         [1032., 1033., 1034., 1035., 1036., 1037., 1038., 1039., 1040.,\n",
       "          1041., 1042., 1043.]]], dtype=float32),\n",
       " array([[[  9.,  10.,  11.,  12.,  13.,  14.,  15.,  16.,  17.,  18.,\n",
       "           19.,  20.],\n",
       "         [ 21.,  22.,  23.,  24.,  25.,  26.,  27.,  28.,  29.,  30.,\n",
       "           31.,  32.],\n",
       "         [ 33.,  34.,  35.,  36.,  37.,  38.,  39.,  40.,  41.,  42.,\n",
       "           43.,  44.],\n",
       "         [ 45.,  46.,  47.,  48.,  49.,  50.,  51.,  52.,  53.,  54.,\n",
       "           55.,  56.],\n",
       "         [ 57.,  58.,  59.,  60.,  61.,  62.,  63.,  64.,  65.,  66.,\n",
       "           67.,  68.],\n",
       "         [ 69.,  70.,  71.,  72.,  73.,  74.,  75.,  76.,  77.,  78.,\n",
       "           79.,  80.]],\n",
       " \n",
       "        [[ 81.,  82.,  83.,  84.,  85.,  86.,  87.,  88.,  89.,  90.,\n",
       "           91.,  92.],\n",
       "         [ 93.,  94.,  95.,  96.,  97.,  98.,  99., 100., 101., 102.,\n",
       "          103., 104.],\n",
       "         [105., 106., 107., 108., 109., 110., 111., 112., 113., 114.,\n",
       "          115., 116.],\n",
       "         [117., 118., 119., 120., 121., 122., 123., 124., 125., 126.,\n",
       "          127., 128.],\n",
       "         [129., 130., 131., 132., 133., 134., 135., 136., 137., 138.,\n",
       "          139., 140.],\n",
       "         [141., 142., 143., 144., 145., 146., 147., 148., 149., 150.,\n",
       "          151., 152.]]], dtype=float32))"
      ]
     },
     "execution_count": 8,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "press_out = 900. + arange(nlevs*nlats*nlons,dtype='float32') # 1d array\n",
    "press_out.shape = (nlevs,nlats,nlons) # reshape to 2d array\n",
    "temp_out = 9. + arange(nlevs*nlats*nlons,dtype='float32') # 1d array\n",
    "temp_out.shape = (nlevs,nlats,nlons) # reshape to 2d array\n",
    "press_out, temp_out"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "5d30d538-280d-47ce-b098-7a2aea33e02c",
   "metadata": {},
   "source": [
    "# create the lat and lon dimensions."
   ]
  },
  {
   "cell_type": "markdown",
   "id": "43dbb289-5b50-4b5c-af68-06bcbd69839d",
   "metadata": {},
   "source": [
    "See http://unidata.github.io/netcdf4-python/#dimensions-in-a-netcdf-file"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 9,
   "id": "3d03e65f-19b3-414f-96c6-5cc316f8c7aa",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "<class 'netCDF4._netCDF4.Dimension'>: name = 'latitude', size = 6"
      ]
     },
     "execution_count": 9,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "ncfile.createDimension('latitude',nlats)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 10,
   "id": "65a75734-3a34-4f93-9710-14fcabe07be6",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "<class 'netCDF4._netCDF4.Dimension'>: name = 'longitude', size = 12"
      ]
     },
     "execution_count": 10,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "ncfile.createDimension('longitude',nlons)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 11,
   "id": "2feefacc-c560-4cd2-9a08-04de6ad2191c",
   "metadata": {},
   "outputs": [],
   "source": [
    "# create level dimension."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 12,
   "id": "06f4bf56-879c-4b49-a048-431fe1f4577d",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "<class 'netCDF4._netCDF4.Dimension'>: name = 'level', size = 2"
      ]
     },
     "execution_count": 12,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "ncfile.createDimension('level',nlevs)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 13,
   "id": "52d7187c-abfa-46c8-a941-65fcef2b497a",
   "metadata": {},
   "outputs": [],
   "source": [
    "# create time dimension (record, or unlimited dimension)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 14,
   "id": "fe64d58a-c027-49a9-935a-b259fa7a9fbe",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "<class 'netCDF4._netCDF4.Dimension'> (unlimited): name = 'time', size = 0"
      ]
     },
     "execution_count": 14,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "ncfile.createDimension('time',None)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "7462db70-a42b-4ff2-962a-bccde802b1f7",
   "metadata": {},
   "outputs": [],
   "source": [
    "# Define the coordinate variables. They will hold the coordinate\n",
    "# information, that is, the latitudes and longitudes.\n",
    "# Coordinate variables only given for lat and lon."
   ]
  },
  {
   "cell_type": "markdown",
   "id": "c3d0fe0d-8a76-4ab5-9019-5fc1de1456c8",
   "metadata": {},
   "source": [
    "See http://unidata.github.io/netcdf4-python/#variables-in-a-netcdf-file"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 15,
   "id": "8198e25e-106d-4986-b4c9-9e56ef5918ee",
   "metadata": {
    "tags": []
   },
   "outputs": [],
   "source": [
    "lats = ncfile.createVariable('latitude',dtype('float32').char,('latitude',))\n",
    "lons = ncfile.createVariable('longitude',dtype('float32').char,('longitude',))"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "ab4d23af-3cfb-4a90-9291-de8917624a17",
   "metadata": {},
   "source": [
    "See http://unidata.github.io/netcdf4-python/#attributes-in-a-netcdf-file"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "3dc18822-f0ac-4083-ab2b-b319a3562f03",
   "metadata": {},
   "outputs": [],
   "source": [
    "# Assign units attributes to coordinate var data. This attaches a\n",
    "# text attribute to each of the coordinate variables, containing the\n",
    "# units."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "bb121eef-1d94-4ae4-af07-56883f69d2c0",
   "metadata": {},
   "outputs": [],
   "source": [
    "lats.units = 'degrees_north'\n",
    "lons.units = 'degrees_east'"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "0824f71f-72fc-4021-b34b-80e32a089858",
   "metadata": {},
   "outputs": [],
   "source": [
    "# write data to coordinate vars."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "9c660a30-6a62-400e-bd3c-712a13623841",
   "metadata": {},
   "outputs": [],
   "source": [
    "lats[:] = lats_out\n",
    "lons[:] = lons_out"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "f7844d03-75f3-4647-b450-d022d417ff66",
   "metadata": {},
   "outputs": [],
   "source": [
    "# create the pressure and temperature variables "
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "3d400abf-cb85-43aa-bfb1-19f231bcd14b",
   "metadata": {},
   "outputs": [],
   "source": [
    "press = ncfile.createVariable('pressure',dtype('float32').char,('time','level','latitude','longitude'))\n",
    "temp = ncfile.createVariable('temperature',dtype('float32').char,('time','level','latitude','longitude'))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "0db011ab-a089-4a0f-aab0-ebc68a6aae5e",
   "metadata": {},
   "outputs": [],
   "source": [
    "# set the units attribute."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "00cf0f06-a854-472b-a8f6-f47b6f7e6f51",
   "metadata": {},
   "outputs": [],
   "source": [
    "press.units =  'hPa'\n",
    "temp.units = 'celsius'"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "c591c60d-e555-4826-a32b-c13786066a08",
   "metadata": {},
   "outputs": [],
   "source": [
    "# write data to variables along record (unlimited) dimension.\n",
    "# same data is written for each record."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "cf61c6bb-2d15-47a6-85bb-3f210aa2f5f8",
   "metadata": {},
   "outputs": [],
   "source": [
    "for nrec in range(nrecs):\n",
    "   press[nrec,:,::] = press_out\n",
    "   temp[nrec,:,::] = temp_out"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "e4149697-cc1c-4896-a7cf-d2debe581f20",
   "metadata": {},
   "outputs": [],
   "source": [
    "# close the file."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "2012c68e-4aee-4777-a72d-9ae57b0569ce",
   "metadata": {},
   "outputs": [],
   "source": [
    "ncfile.close()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "df91a6a9-69ff-4ac1-9a9e-dc3e3a230206",
   "metadata": {},
   "outputs": [],
   "source": [
    "print ('*** SUCCESS writing example file pres_temp_4D.nc')"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "e4215649-b36f-45de-9bed-cd620944d70b",
   "metadata": {},
   "outputs": [],
   "source": []
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "2d9719db-994e-4a35-82b6-3761f7891975",
   "metadata": {},
   "outputs": [],
   "source": []
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "26103d19-8ff3-4db6-842f-274cd15838a1",
   "metadata": {},
   "outputs": [],
   "source": []
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "9f5cdf13-df2f-4e44-9740-6e173a2121ba",
   "metadata": {},
   "outputs": [],
   "source": []
  }
 ],
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