{
"cells": [
{
"cell_type": "markdown",
"metadata": {},
"source": [
"# xncml usage\n",
"\n",
"xncml serves two purposes: modifying NcML files, and opening NcML files as an `xarray.Dataset`. "
]
},
{
"cell_type": "code",
"execution_count": 1,
"metadata": {
"is_executing": true
},
"outputs": [],
"source": [
"import xncml\n",
"from pathlib import Path\n",
"from IPython.display import Code"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"## Modify an NcML document\n",
"\n",
"``xncml`` can add or remove global and variable attributes, and remove variables and dimensions. It can also be used to create NcML files from scratch. This is all done using the `xncml.Dataset` class and its methods.\n",
"\n",
"### Create an Ncml Dataset object from a local NcML file\n",
"\n",
"The `xncml.Dataset` class is instantiated by passing the NcML file location. Alternatively, the class can be created using its `from_text` classmethod."
]
},
{
"cell_type": "code",
"execution_count": 2,
"metadata": {},
"outputs": [
{
"data": {
"text/html": [
"<?xml version="1.0" encoding="utf-8"?> \n",
"<netcdf location= "nc/example1.nc" xmlns= "http://www.unidata.ucar.edu/namespaces/netcdf/ncml-2.2" > \n",
"\t<dimension name= "time" length= "2" isUnlimited= "true" ></dimension> \n",
"\t<dimension name= "lat" length= "3" ></dimension> \n",
"\t<dimension name= "lon" length= "4" ></dimension> \n",
"\t<attribute name= "title" type= "String" value= "Example Data" ></attribute> \n",
"\t<variable name= "rh" shape= "time lat lon" type= "int" > \n",
"\t\t<attribute name= "long_name" type= "String" value= "relative humidity" ></attribute> \n",
"\t\t<attribute name= "units" type= "String" value= "percent" ></attribute> \n",
"\t</variable> \n",
"\t<variable name= "T" shape= "time lat lon" type= "double" > \n",
"\t\t<attribute name= "long_name" type= "String" value= "surface temperature" ></attribute> \n",
"\t\t<attribute name= "units" type= "String" value= "C" ></attribute> \n",
"\t</variable> \n",
"\t<variable name= "lat" shape= "lat" type= "float" > \n",
"\t\t<attribute name= "units" type= "String" value= "degrees_north" ></attribute> \n",
"\t\t<values> 41.0 40.0 39.0</values> \n",
"\t</variable> \n",
"\t<variable name= "lon" shape= "lon" type= "float" > \n",
"\t\t<attribute name= "units" type= "String" value= "degrees_east" ></attribute> \n",
"\t\t<values> -109.0 -107.0 -105.0 -103.0</values> \n",
"\t</variable> \n",
"\t<variable name= "time" shape= "time" type= "int" > \n",
"\t\t<attribute name= "units" type= "String" value= "hours" ></attribute> \n",
"\t\t<values> 6 18</values> \n",
"\t</variable> \n",
"</netcdf> \n",
"\n",
"\t\n",
"\t\t \n",
"\t\n",
"\t\t \n",
"\t\n",
"\t\t41.0 40.0 39.0 \n",
"\t \n",
"\t\n",
"\t\t-109.0 -107.0 -105.0 -103.0 \n",
"\t \n",
"\t\n",
"\t\t6 18 \n",
"\t \n",
" "
]
},
"execution_count": 2,
"metadata": {},
"output_type": "execute_result"
}
],
"source": [
"fn = Path(xncml.__file__).parent.parent / \"tests\" / \"data\" / \"exercise1.ncml\"\n",
"\n",
"# Instantiate Dataset class from the file location. An alternative would have been to do\n",
"# nc = xncml.Dataset.from_text(fn.read_text())\n",
"nc = xncml.Dataset(fn)\n",
"\n",
"\n",
"# This is just to pretty print the XML\n",
"Code(repr(nc), language=\"XML\")"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"### Create an NcML Dataset modifying a netCDF file\n",
"\n",
"Here we're creating an empty NcML dataset from scratch, in which we can include modifying statements that will apply to an existing netCDF dataset identified by the `location` argument."
]
},
{
"cell_type": "code",
"execution_count": 3,
"metadata": {},
"outputs": [
{
"data": {
"text/html": [
"<?xml version="1.0" encoding="utf-8"?> \n",
"<netcdf xmlns= "http://www.unidata.ucar.edu/namespaces/netcdf/ncml-2.2" location= "nc/example1.nc" ></netcdf> \n",
"<?xml version="1.0" encoding="utf-8"?> \n",
"<netcdf location= "nc/example1.nc" xmlns= "http://www.unidata.ucar.edu/namespaces/netcdf/ncml-2.2" > \n",
"\t<dimension name= "time" length= "2" isUnlimited= "true" ></dimension> \n",
"\t<dimension name= "lat" length= "3" ></dimension> \n",
"\t<dimension name= "lon" length= "4" ></dimension> \n",
"\t<attribute name= "title" type= "String" value= "Example Data" ></attribute> \n",
"\t<variable name= "rh" shape= "time lat lon" type= "int" > \n",
"\t\t<attribute name= "long_name" type= "String" value= "relative humidity" ></attribute> \n",
"\t\t<attribute name= "units" type= "String" value= "percent" ></attribute> \n",
"\t</variable> \n",
"\t<variable name= "Temp" shape= "time lat lon" type= "double" orgName= "T" > \n",
"\t\t<attribute name= "long_name" type= "String" value= "surface temperature" ></attribute> \n",
"\t\t<attribute name= "units" type= "String" value= "C" ></attribute> \n",
"\t</variable> \n",
"\t<variable name= "lat" shape= "lat" type= "float" > \n",
"\t\t<attribute name= "units" type= "String" value= "degrees_north" ></attribute> \n",
"\t\t<values> 41.0 40.0 39.0</values> \n",
"\t</variable> \n",
"\t<variable name= "lon" shape= "lon" type= "float" > \n",
"\t\t<attribute name= "units" type= "String" value= "degrees_east" ></attribute> \n",
"\t\t<values> -109.0 -107.0 -105.0 -103.0</values> \n",
"\t</variable> \n",
"\t<variable name= "time" shape= "time" type= "int" > \n",
"\t\t<attribute name= "units" type= "String" value= "hours" ></attribute> \n",
"\t\t<values> 6 18</values> \n",
"\t</variable> \n",
"</netcdf> \n",
"\n",
"\t\n",
"\t\t \n",
"\t\n",
"\t\t \n",
"\t\n",
"\t\t41.0 40.0 39.0 \n",
"\t \n",
"\t\n",
"\t\t-109.0 -107.0 -105.0 -103.0 \n",
"\t \n",
"\t\n",
"\t\t6 18 \n",
"\t \n",
" "
]
},
"execution_count": 4,
"metadata": {},
"output_type": "execute_result"
}
],
"source": [
"nc.rename_variable('T', 'Temp')\n",
"Code(repr(nc), language=\"XML\")"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"### Remove the variable `Temp` from the dataset"
]
},
{
"cell_type": "code",
"execution_count": 5,
"metadata": {},
"outputs": [
{
"data": {
"text/html": [
"<?xml version="1.0" encoding="utf-8"?> \n",
"<netcdf location= "nc/example1.nc" xmlns= "http://www.unidata.ucar.edu/namespaces/netcdf/ncml-2.2" > \n",
"\t<dimension name= "time" length= "2" isUnlimited= "true" ></dimension> \n",
"\t<dimension name= "lat" length= "3" ></dimension> \n",
"\t<dimension name= "lon" length= "4" ></dimension> \n",
"\t<attribute name= "title" type= "String" value= "Example Data" ></attribute> \n",
"\t<variable name= "rh" shape= "time lat lon" type= "int" > \n",
"\t\t<attribute name= "long_name" type= "String" value= "relative humidity" ></attribute> \n",
"\t\t<attribute name= "units" type= "String" value= "percent" ></attribute> \n",
"\t</variable> \n",
"\t<variable name= "Temp" shape= "time lat lon" type= "double" orgName= "T" > \n",
"\t\t<attribute name= "long_name" type= "String" value= "surface temperature" ></attribute> \n",
"\t\t<attribute name= "units" type= "String" value= "C" ></attribute> \n",
"\t</variable> \n",
"\t<variable name= "lat" shape= "lat" type= "float" > \n",
"\t\t<attribute name= "units" type= "String" value= "degrees_north" ></attribute> \n",
"\t\t<values> 41.0 40.0 39.0</values> \n",
"\t</variable> \n",
"\t<variable name= "lon" shape= "lon" type= "float" > \n",
"\t\t<attribute name= "units" type= "String" value= "degrees_east" ></attribute> \n",
"\t\t<values> -109.0 -107.0 -105.0 -103.0</values> \n",
"\t</variable> \n",
"\t<variable name= "time" shape= "time" type= "int" > \n",
"\t\t<attribute name= "units" type= "String" value= "hours" ></attribute> \n",
"\t\t<values> 6 18</values> \n",
"\t</variable> \n",
"\t<remove name= "Temp" type= "variable" ></remove> \n",
"</netcdf> \n",
"\n",
"\t\n",
"\t\t \n",
"\t\n",
"\t\t \n",
"\t\n",
"\t\t41.0 40.0 39.0 \n",
"\t \n",
"\t\n",
"\t\t-109.0 -107.0 -105.0 -103.0 \n",
"\t \n",
"\t\n",
"\t\t6 18 \n",
"\t \n",
"\t "
]
},
"execution_count": 5,
"metadata": {},
"output_type": "execute_result"
}
],
"source": [
"nc.remove_variable('Temp')\n",
"Code(repr(nc), language=\"XML\")"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"### Remove the attribute `units` from the variable `Temp`"
]
},
{
"cell_type": "code",
"execution_count": 6,
"metadata": {},
"outputs": [
{
"data": {
"text/html": [
"<?xml version="1.0" encoding="utf-8"?> \n",
"<netcdf location= "nc/example1.nc" xmlns= "http://www.unidata.ucar.edu/namespaces/netcdf/ncml-2.2" > \n",
"\t<dimension name= "time" length= "2" isUnlimited= "true" ></dimension> \n",
"\t<dimension name= "lat" length= "3" ></dimension> \n",
"\t<dimension name= "lon" length= "4" ></dimension> \n",
"\t<attribute name= "title" type= "String" value= "Example Data" ></attribute> \n",
"\t<variable name= "rh" shape= "time lat lon" type= "int" > \n",
"\t\t<attribute name= "long_name" type= "String" value= "relative humidity" ></attribute> \n",
"\t\t<attribute name= "units" type= "String" value= "percent" ></attribute> \n",
"\t</variable> \n",
"\t<variable name= "Temp" shape= "time lat lon" type= "double" orgName= "T" > \n",
"\t\t<attribute name= "long_name" type= "String" value= "surface temperature" ></attribute> \n",
"\t\t<attribute name= "units" type= "String" value= "C" ></attribute> \n",
"\t\t<remove name= "units" type= "attribute" ></remove> \n",
"\t</variable> \n",
"\t<variable name= "lat" shape= "lat" type= "float" > \n",
"\t\t<attribute name= "units" type= "String" value= "degrees_north" ></attribute> \n",
"\t\t<values> 41.0 40.0 39.0</values> \n",
"\t</variable> \n",
"\t<variable name= "lon" shape= "lon" type= "float" > \n",
"\t\t<attribute name= "units" type= "String" value= "degrees_east" ></attribute> \n",
"\t\t<values> -109.0 -107.0 -105.0 -103.0</values> \n",
"\t</variable> \n",
"\t<variable name= "time" shape= "time" type= "int" > \n",
"\t\t<attribute name= "units" type= "String" value= "hours" ></attribute> \n",
"\t\t<values> 6 18</values> \n",
"\t</variable> \n",
"\t<remove name= "Temp" type= "variable" ></remove> \n",
"</netcdf> \n",
"\n",
"\t\n",
"\t\t \n",
"\t\n",
"\t\t \n",
"\t\n",
"\t\t41.0 40.0 39.0 \n",
"\t \n",
"\t\n",
"\t\t-109.0 -107.0 -105.0 -103.0 \n",
"\t \n",
"\t\n",
"\t\t6 18 \n",
"\t \n",
"\t "
]
},
"execution_count": 6,
"metadata": {},
"output_type": "execute_result"
}
],
"source": [
"nc.remove_variable_attribute(variable='Temp', key='units')\n",
"Code(repr(nc), language=\"XML\")"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"### Remove the global `title` attribute from the dataset"
]
},
{
"cell_type": "code",
"execution_count": 7,
"metadata": {},
"outputs": [
{
"data": {
"text/html": [
"<?xml version="1.0" encoding="utf-8"?> \n",
"<netcdf location= "nc/example1.nc" xmlns= "http://www.unidata.ucar.edu/namespaces/netcdf/ncml-2.2" > \n",
"\t<dimension name= "time" length= "2" isUnlimited= "true" ></dimension> \n",
"\t<dimension name= "lat" length= "3" ></dimension> \n",
"\t<dimension name= "lon" length= "4" ></dimension> \n",
"\t<attribute name= "title" type= "String" value= "Example Data" ></attribute> \n",
"\t<variable name= "rh" shape= "time lat lon" type= "int" > \n",
"\t\t<attribute name= "long_name" type= "String" value= "relative humidity" ></attribute> \n",
"\t\t<attribute name= "units" type= "String" value= "percent" ></attribute> \n",
"\t</variable> \n",
"\t<variable name= "Temp" shape= "time lat lon" type= "double" orgName= "T" > \n",
"\t\t<attribute name= "long_name" type= "String" value= "surface temperature" ></attribute> \n",
"\t\t<attribute name= "units" type= "String" value= "C" ></attribute> \n",
"\t\t<remove name= "units" type= "attribute" ></remove> \n",
"\t</variable> \n",
"\t<variable name= "lat" shape= "lat" type= "float" > \n",
"\t\t<attribute name= "units" type= "String" value= "degrees_north" ></attribute> \n",
"\t\t<values> 41.0 40.0 39.0</values> \n",
"\t</variable> \n",
"\t<variable name= "lon" shape= "lon" type= "float" > \n",
"\t\t<attribute name= "units" type= "String" value= "degrees_east" ></attribute> \n",
"\t\t<values> -109.0 -107.0 -105.0 -103.0</values> \n",
"\t</variable> \n",
"\t<variable name= "time" shape= "time" type= "int" > \n",
"\t\t<attribute name= "units" type= "String" value= "hours" ></attribute> \n",
"\t\t<values> 6 18</values> \n",
"\t</variable> \n",
"\t<remove name= "Temp" type= "variable" ></remove> \n",
"\t<remove name= "title" type= "attribute" ></remove> \n",
"</netcdf> \n",
"\n",
"\t\n",
"\t\t \n",
"\t\n",
"\t\t \n",
"\t\n",
"\t\t41.0 40.0 39.0 \n",
"\t \n",
"\t\n",
"\t\t-109.0 -107.0 -105.0 -103.0 \n",
"\t \n",
"\t\n",
"\t\t6 18 \n",
"\t \n",
"\t "
]
},
"execution_count": 7,
"metadata": {},
"output_type": "execute_result"
}
],
"source": [
"nc.remove_dataset_attribute('title')\n",
"Code(repr(nc), language=\"XML\")"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"### Add a global `history` attribute"
]
},
{
"cell_type": "code",
"execution_count": 8,
"metadata": {},
"outputs": [
{
"data": {
"text/html": [
"<?xml version="1.0" encoding="utf-8"?> \n",
"<netcdf location= "nc/example1.nc" xmlns= "http://www.unidata.ucar.edu/namespaces/netcdf/ncml-2.2" > \n",
"\t<dimension name= "time" length= "2" isUnlimited= "true" ></dimension> \n",
"\t<dimension name= "lat" length= "3" ></dimension> \n",
"\t<dimension name= "lon" length= "4" ></dimension> \n",
"\t<attribute name= "title" type= "String" value= "Example Data" ></attribute> \n",
"\t<attribute name= "Conventions" type= "String" value= "CF-2.0" ></attribute> \n",
"\t<variable name= "rh" shape= "time lat lon" type= "int" > \n",
"\t\t<attribute name= "long_name" type= "String" value= "relative humidity" ></attribute> \n",
"\t\t<attribute name= "units" type= "String" value= "percent" ></attribute> \n",
"\t</variable> \n",
"\t<variable name= "Temp" shape= "time lat lon" type= "double" orgName= "T" > \n",
"\t\t<attribute name= "long_name" type= "String" value= "surface temperature" ></attribute> \n",
"\t\t<attribute name= "units" type= "String" value= "C" ></attribute> \n",
"\t\t<remove name= "units" type= "attribute" ></remove> \n",
"\t</variable> \n",
"\t<variable name= "lat" shape= "lat" type= "float" > \n",
"\t\t<attribute name= "units" type= "String" value= "degrees_north" ></attribute> \n",
"\t\t<values> 41.0 40.0 39.0</values> \n",
"\t</variable> \n",
"\t<variable name= "lon" shape= "lon" type= "float" > \n",
"\t\t<attribute name= "units" type= "String" value= "degrees_east" ></attribute> \n",
"\t\t<values> -109.0 -107.0 -105.0 -103.0</values> \n",
"\t</variable> \n",
"\t<variable name= "time" shape= "time" type= "int" > \n",
"\t\t<attribute name= "units" type= "String" value= "hours" ></attribute> \n",
"\t\t<values> 6 18</values> \n",
"\t</variable> \n",
"\t<remove name= "Temp" type= "variable" ></remove> \n",
"\t<remove name= "title" type= "attribute" ></remove> \n",
"</netcdf> \n",
"\n",
"\t\n",
"\t\t \n",
"\t\n",
"\t\t \n",
"\t\n",
"\t\t41.0 40.0 39.0 \n",
"\t \n",
"\t\n",
"\t\t-109.0 -107.0 -105.0 -103.0 \n",
"\t \n",
"\t\n",
"\t\t6 18 \n",
"\t \n",
"\t "
]
},
"execution_count": 8,
"metadata": {},
"output_type": "execute_result"
}
],
"source": [
"nc.add_dataset_attribute(key='Conventions', value='CF-2.0')\n",
"Code(repr(nc), language=\"XML\")"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"### Rename a global attribute"
]
},
{
"cell_type": "code",
"execution_count": 9,
"metadata": {},
"outputs": [
{
"data": {
"text/html": [
"<?xml version="1.0" encoding="utf-8"?> \n",
"<netcdf location= "nc/example1.nc" xmlns= "http://www.unidata.ucar.edu/namespaces/netcdf/ncml-2.2" > \n",
"\t<dimension name= "time" length= "2" isUnlimited= "true" ></dimension> \n",
"\t<dimension name= "lat" length= "3" ></dimension> \n",
"\t<dimension name= "lon" length= "4" ></dimension> \n",
"\t<attribute name= "title" type= "String" value= "Example Data" ></attribute> \n",
"\t<attribute name= "Conventions" type= "String" value= "CF-2.0" ></attribute> \n",
"\t<attribute name= "source" > \n",
"\t\t<orgName> Source</orgName> \n",
"\t</attribute> \n",
"\t<variable name= "rh" shape= "time lat lon" type= "int" > \n",
"\t\t<attribute name= "long_name" type= "String" value= "relative humidity" ></attribute> \n",
"\t\t<attribute name= "units" type= "String" value= "percent" ></attribute> \n",
"\t</variable> \n",
"\t<variable name= "Temp" shape= "time lat lon" type= "double" orgName= "T" > \n",
"\t\t<attribute name= "long_name" type= "String" value= "surface temperature" ></attribute> \n",
"\t\t<attribute name= "units" type= "String" value= "C" ></attribute> \n",
"\t\t<remove name= "units" type= "attribute" ></remove> \n",
"\t</variable> \n",
"\t<variable name= "lat" shape= "lat" type= "float" > \n",
"\t\t<attribute name= "units" type= "String" value= "degrees_north" ></attribute> \n",
"\t\t<values> 41.0 40.0 39.0</values> \n",
"\t</variable> \n",
"\t<variable name= "lon" shape= "lon" type= "float" > \n",
"\t\t<attribute name= "units" type= "String" value= "degrees_east" ></attribute> \n",
"\t\t<values> -109.0 -107.0 -105.0 -103.0</values> \n",
"\t</variable> \n",
"\t<variable name= "time" shape= "time" type= "int" > \n",
"\t\t<attribute name= "units" type= "String" value= "hours" ></attribute> \n",
"\t\t<values> 6 18</values> \n",
"\t</variable> \n",
"\t<remove name= "Temp" type= "variable" ></remove> \n",
"\t<remove name= "title" type= "attribute" ></remove> \n",
"</netcdf> \n",
"\n",
"\t\n",
"\t\tSource \n",
"\t \n",
"\t\n",
"\t\t \n",
"\t\n",
"\t\t \n",
"\t\n",
"\t\t41.0 40.0 39.0 \n",
"\t \n",
"\t\n",
"\t\t-109.0 -107.0 -105.0 -103.0 \n",
"\t \n",
"\t\n",
"\t\t6 18 \n",
"\t \n",
"\t "
]
},
"execution_count": 9,
"metadata": {},
"output_type": "execute_result"
}
],
"source": [
"nc.rename_dataset_attribute(old_name=\"Source\", new_name=\"source\")\n",
"Code(repr(nc), language=\"XML\")"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"### Add a variable attribute"
]
},
{
"cell_type": "code",
"execution_count": 10,
"metadata": {},
"outputs": [
{
"data": {
"text/html": [
"<?xml version="1.0" encoding="utf-8"?> \n",
"<netcdf location= "nc/example1.nc" xmlns= "http://www.unidata.ucar.edu/namespaces/netcdf/ncml-2.2" > \n",
"\t<dimension name= "time" length= "2" isUnlimited= "true" ></dimension> \n",
"\t<dimension name= "lat" length= "3" ></dimension> \n",
"\t<dimension name= "lon" length= "4" ></dimension> \n",
"\t<attribute name= "title" type= "String" value= "Example Data" ></attribute> \n",
"\t<attribute name= "Conventions" type= "String" value= "CF-2.0" ></attribute> \n",
"\t<attribute name= "source" > \n",
"\t\t<orgName> Source</orgName> \n",
"\t</attribute> \n",
"\t<variable name= "rh" shape= "time lat lon" type= "int" > \n",
"\t\t<attribute name= "long_name" type= "String" value= "relative humidity" ></attribute> \n",
"\t\t<attribute name= "units" type= "String" value= "percent" ></attribute> \n",
"\t</variable> \n",
"\t<variable name= "Temp" shape= "time lat lon" type= "double" orgName= "T" > \n",
"\t\t<attribute name= "long_name" type= "String" value= "surface temperature" ></attribute> \n",
"\t\t<attribute name= "units" type= "String" value= "Kelvin" ></attribute> \n",
"\t\t<attribute name= "Fill_value" type= "String" value= "-999999999.0" ></attribute> \n",
"\t\t<remove name= "units" type= "attribute" ></remove> \n",
"\t</variable> \n",
"\t<variable name= "lat" shape= "lat" type= "float" > \n",
"\t\t<attribute name= "units" type= "String" value= "degrees_north" ></attribute> \n",
"\t\t<values> 41.0 40.0 39.0</values> \n",
"\t</variable> \n",
"\t<variable name= "lon" shape= "lon" type= "float" > \n",
"\t\t<attribute name= "units" type= "String" value= "degrees_east" ></attribute> \n",
"\t\t<values> -109.0 -107.0 -105.0 -103.0</values> \n",
"\t</variable> \n",
"\t<variable name= "time" shape= "time" type= "int" > \n",
"\t\t<attribute name= "units" type= "String" value= "hours" ></attribute> \n",
"\t\t<values> 6 18</values> \n",
"\t</variable> \n",
"\t<remove name= "Temp" type= "variable" ></remove> \n",
"\t<remove name= "title" type= "attribute" ></remove> \n",
"</netcdf> \n",
"\n",
"\t\n",
"\t\tSource \n",
"\t \n",
"\t\n",
"\t\t \n",
"\t\n",
"\t\t \n",
"\t\n",
"\t\t41.0 40.0 39.0 \n",
"\t \n",
"\t\n",
"\t\t-109.0 -107.0 -105.0 -103.0 \n",
"\t \n",
"\t\n",
"\t\t6 18 \n",
"\t \n",
"\t "
]
},
"execution_count": 10,
"metadata": {},
"output_type": "execute_result"
}
],
"source": [
"nc.add_variable_attribute(variable='Temp', key='units', value='Kelvin')\n",
"nc.add_variable_attribute(variable='Temp', key='Fill_value', value=-999999999.)\n",
"Code(repr(nc), language=\"XML\")"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"### Write Dataset back to an ncml file"
]
},
{
"cell_type": "code",
"execution_count": 11,
"metadata": {},
"outputs": [],
"source": [
"import tempfile\n",
"tmp_fn = Path(tempfile.mkdtemp()) / \"exercise1_modified.ncml\"\n",
"nc.to_ncml(tmp_fn)"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"### Export metadata to a dictionary\n",
"`Dataset` has a `to_cf_dict` method that returns a dictionary following the [CF-JSON](https://cf-json.org/specification) specifications. The output may not always be fully compliant with the CF-JSON specification because NcML files used to create virtual datasets do not always include all information that CF-JSON expects.\n"
]
},
{
"cell_type": "code",
"execution_count": 12,
"metadata": {},
"outputs": [
{
"data": {
"text/plain": [
"OrderedDict([('@location', 'nc/example1.nc'),\n",
" ('@xmlns',\n",
" {'': 'http://www.unidata.ucar.edu/namespaces/netcdf/ncml-2.2'}),\n",
" ('dimensions',\n",
" OrderedDict([('time', 2), ('lat', 3), ('lon', 4)])),\n",
" ('attributes',\n",
" OrderedDict([('title', 'Example Data'),\n",
" ('Conventions', 'CF-2.0'),\n",
" ('source', None)])),\n",
" ('variables',\n",
" OrderedDict([('lat',\n",
" OrderedDict([('shape', ['lat']),\n",
" ('type', 'float'),\n",
" ('attributes',\n",
" OrderedDict([('units',\n",
" 'degrees_north')])),\n",
" ('data', [41.0, 40.0, 39.0])])),\n",
" ('lon',\n",
" OrderedDict([('shape', ['lon']),\n",
" ('type', 'float'),\n",
" ('attributes',\n",
" OrderedDict([('units',\n",
" 'degrees_east')])),\n",
" ('data',\n",
" [-109.0, -107.0, -105.0, -103.0])])),\n",
" ('time',\n",
" OrderedDict([('shape', ['time']),\n",
" ('type', 'int'),\n",
" ('attributes',\n",
" OrderedDict([('units', 'hours')])),\n",
" ('data', [6, 18])])),\n",
" ('rh',\n",
" OrderedDict([('shape', ['time', 'lat', 'lon']),\n",
" ('type', 'int'),\n",
" ('attributes',\n",
" OrderedDict([('long_name',\n",
" 'relative humidity'),\n",
" ('units',\n",
" 'percent')]))])),\n",
" ('Temp',\n",
" OrderedDict([('shape', ['time', 'lat', 'lon']),\n",
" ('type', 'double'),\n",
" ('attributes',\n",
" OrderedDict([('long_name',\n",
" 'surface temperature'),\n",
" ('units', 'Kelvin'),\n",
" ('Fill_value',\n",
" -999999999.0)]))]))]))])"
]
},
"execution_count": 12,
"metadata": {},
"output_type": "execute_result"
}
],
"source": [
"nc.to_cf_dict()"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"## Open an NcML document as an ``xarray.Dataset``\n",
"\n",
"``xncml`` can parse NcML instructions to create an ``xarray.Dataset``. Calling the `close` method on the returned dataset will close all underlying netCDF files referred to by the NcML document. Note that a few NcML instructions are not yet supported."
]
},
{
"cell_type": "code",
"execution_count": 13,
"metadata": {},
"outputs": [
{
"data": {
"text/html": [
"\n",
"\n",
"\n",
" \n",
"\n",
" \n",
" \n",
" \n",
"
<xarray.Dataset>\n",
"Dimensions: (time: 2, lat: 3, lon: 4)\n",
"Coordinates:\n",
" * lat (lat) float32 41.0 40.0 39.0\n",
" * lon (lon) float32 -109.0 -107.0 -105.0 -103.0\n",
" * time (time) int32 6 18\n",
"Data variables:\n",
" rh (time, lat, lon) int32 1 2 3 4 5 6 7 8 ... 25 26 27 28 29 30 31 32\n",
" T (time, lat, lon) float64 1.0 2.0 3.0 4.0 2.0 ... 7.5 15.0 22.5 30.0\n",
"Attributes:\n",
" title: Example Data \n",
"Dimensions: (time: 2, lat: 3, lon: 4)\n",
"Coordinates:\n",
" * lat (lat) float32 41.0 40.0 39.0\n",
" * lon (lon) float32 -109.0 -107.0 -105.0 -103.0\n",
" * time (time) int32 6 18\n",
"Data variables:\n",
" rh (time, lat, lon) int32 1 2 3 4 5 6 7 8 ... 25 26 27 28 29 30 31 32\n",
" T (time, lat, lon) float64 1.0 2.0 3.0 4.0 2.0 ... 7.5 15.0 22.5 30.0\n",
"Attributes:\n",
" title: Example Data"
]
},
"execution_count": 13,
"metadata": {},
"output_type": "execute_result"
}
],
"source": [
"xncml.open_ncml(fn)"
]
}
],
"metadata": {
"kernelspec": {
"display_name": "Python 3 (ipykernel)",
"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",
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