podpac.data.DataSource

class podpac.data.DataSource(**kwargs)

Bases: podpac.core.node.Node

Base node for any data obtained directly from a single source.

Parameters

• source (Any) – The location of the source. Depending on the child node this can be a filepath, numpy array, or dictionary as a few examples.

• coordinates (podpac.Coordinates) – The coordinates of the data source.

• nan_vals (List, optional) – List of values from source data that should be interpreted as ‘no data’ or ‘nans’

• coordinate_index_type (str, optional) – Type of index to use for data source. Possible values are ['slice', 'numpy'] Default is ‘numpy’, which allows a tuple of integer indices.

• cache_coordinates (bool) – Whether to cache coordinates using the podpac cache_ctrl. Default False.

• cache_output (bool) – Should the node’s output be cached? If not provided or None, uses default based on settings[“CACHE_DATASOURCE_OUTPUT_DEFAULT”]. If True, outputs will be cached and retrieved from cache. If False, outputs will not be cached OR retrieved from cache (even if they exist in cache).

Notes

Custom DataSource Nodes must implement the get_data() and get_coordinates() methods.

Alternative Constructors

from_definition(definition)	Create podpac Node from a dictionary definition.
from_json(s)	Create podpac Node from a JSON definition.

Methods

__init__(**kwargs)	Do not overwrite me
create_output_array(coords[, data, attrs])	Initialize an output data array
eval(coordinates, **kwargs)	Evaluate the node at the given coordinates.
eval_group(group)	Evaluate the node for each of the coordinates in the group.
find_coordinates()	Get the available coordinates for the Node.
from_url(url)	Create podpac Node from a WMS/WCS request.
get_cache(key[, coordinates])	Get cached data for this node.
get_coordinates()	Returns a Coordinates object that describes the coordinates of the data source.
get_data(coordinates, coordinates_index)	This method must be defined by the data source implementing the DataSource class.
has_cache(key[, coordinates])	Check for cached data for this node.
init()	Overwrite this method if a node needs to do any additional initialization after the standard initialization.
load(path)	Create podpac Node from file.
put_cache(data, key[, coordinates, expires, …])	Cache data for this node.
rem_cache(key[, coordinates, mode])	Clear cached data for this node.
save(path)	Write node to file.
set_coordinates(coordinates[, force])	Set the coordinates.
trait_defaults(*names, **metadata)	Return a trait’s default value or a dictionary of them
trait_has_value(name)	Returns True if the specified trait has a value.
trait_is_defined(name)
trait_values(**metadata)	A dict of trait names and their values.

Attributes

attrs	List of node attributes
base_ref	Default reference/name in node definitions
boundary	An instance of a Python dict.
cache_coordinates	A boolean (True, False) trait.
cache_ctrl	A trait whose value must be an instance of a specified class.
cache_output	A boolean (True, False) trait.
coordinate_index_type	An enum whose value must be in a given sequence.
coordinates	{coordinates}
definition
dtype	A trait which allows any value.
force_eval	A boolean (True, False) trait.
hash	hash for this node, used in caching and to determine equality.
json	Definition for this node in JSON format.
json_pretty	Definition for this node in JSON format, with indentation suitable for display.
nan_vals	An instance of a Python list.
output	A trait for unicode strings.
outputs	An instance of a Python list.
style	A trait whose value must be an instance of a specified class.
units	A trait for unicode strings.

Members

__init__(**kwargs)

Do not overwrite me

boundary

An instance of a Python dict.

One or more traits can be passed to the constructor to validate the keys and/or values of the dict. If you need more detailed validation, you may use a custom validator method.

Changed in version 5.0: Added key_trait for validating dict keys.

Changed in version 5.0: Deprecated ambiguous trait, traits args in favor of value_trait, per_key_traits.

cache_coordinates

A boolean (True, False) trait.

cache_output

A boolean (True, False) trait.

coordinate_index_type

An enum whose value must be in a given sequence.

property coordinates

{coordinates}

find_coordinates()

Get the available coordinates for the Node. For a DataSource, this is just the coordinates.

Returns

coords_list – singleton list containing the coordinates (Coordinates object)

Return type

list

get_coordinates()

Returns a Coordinates object that describes the coordinates of the data source.

In most cases, this method is defined by the data source implementing the DataSource class. If method is not implemented by the data source, it will try to return self.coordinates if self.coordinates is not None.

Otherwise, this method will raise a NotImplementedError.

Returns

The coordinates describing the data source array.

Return type

podpac.Coordinates

Notes

Need to pay attention to: - the order of the dimensions - the stacking of the dimension - the type of coordinates

Coordinates should be non-nan and non-repeating for best compatibility

Raises

NotImplementedError – This needs to be implemented by derived classes

get_data(coordinates, coordinates_index)

This method must be defined by the data source implementing the DataSource class. When data source nodes are evaluated, this method is called with request coordinates and coordinate indexes. The implementing method can choose which input provides the most efficient method of getting data (i.e via coordinates or via the index of the coordinates).

Coordinates and coordinate indexes may be strided or subsets of the source data, but all coordinates and coordinate indexes will match 1:1 with the subset data.

This method may return a numpy array, an xarray DaraArray, or a podpac UnitsDataArray. If a numpy array or xarray DataArray is returned, podpac.data.DataSource.evaluate() will cast the data into a UnitsDataArray using the requested source coordinates. If a podpac UnitsDataArray is passed back, the podpac.data.DataSource.evaluate() method will not do any further processing. The inherited Node method create_output_array can be used to generate the template UnitsDataArray in your DataSource. See podpac.Node.create_output_array() for more details.

Parameters

• coordinates (podpac.Coordinates) – The coordinates that need to be retrieved from the data source using the coordinate system of the data source

• coordinates_index (List) – A list of slices or a boolean array that give the indices of the data that needs to be retrieved from the data source. The values in the coordinate_index will vary depending on the coordinate_index_type defined for the data source.

Returns

A subset of the returned data. If a numpy array or xarray DataArray is returned, the data will be cast into UnitsDataArray using the returned data to fill values at the requested source coordinates.

Return type

np.ndarray, xr.DataArray, podpac.UnitsDataArray

Raises

NotImplementedError – This needs to be implemented by derived classes

nan_vals

An instance of a Python list.

set_coordinates(coordinates, force=False)

Set the coordinates. Used by Compositors as an optimization.

Parameters

• coordinates (podpac.Coordinates) – Coordinates to set. Usually these are coordinates that are shared across compositor sources.

• NOTE (This is only currently used by SMAPCompositor. It should potentially be moved to the SMAPSource.) –