Objects

Objects are the units which hold data in pdc. They are one or multi dimensional arrays of data with a single type. Example of creation and usage:

 1import pdc
 2from pdc import Object
 3import numpy as np
 4
 5with pdc.ServerContext():
 6   pdc.init()
 7   #create temporary container
 8   cont = pdc.Container('cont', lifetime=pdc.Container.Lifetime.TRANSIENT)
 9
10   #create np data array of 128 doubles
11   data = np.full(128, 1.0, dtype=np.float64)
12
13   #Method 1: create object from array:
14   obj1 = cont.object_from_array('objectexample_obj1', data)
15
16   out_data = obj1.get_data().wait()
17   for val in out_data:
18      assert val == 1.0
19
20   #Method 2: create object from properties:
21   #create object property
22   prop = Object.Properties(dims=128, type=pdc.Type.DOUBLE)
23   #alternatively:
24   prop = Object.Properties(dims=128, type=np.double)
25
26   #property objects can be changed like so:
27   prop.app_name = 'objectexample'
28
29   #create object
30   obj2 = cont.create_object('objectexample_obj2', prop)
31
32   #set all data to data
33   obj2.set_data(data).wait()
34
35   #test data values
36   out_data = obj2.get_data().wait()
37   for val in out_data:
38      assert val == 1.0
class pdc.Object(*args)

A PDC object

class Properties(self, dims:Union[Tuple[uint32, ...], uint32], type, uint32_t time_step:uint32=0, user_id:Optional[uint32]=None, str app_name:str='')

Contains most of the metadata associated with an object. This is an inner class of Object

Parameters:

  • dims (Tuple[uint32, ...] or uint32) – A tuple containing dimensions of the object, or a single integer for 1-D objects. For example, (10, 3) means 10 rows and 3 columns. 1 <= len(dims) <= 2^31-1

  • type (Type) – the data type. Either an instance of Type, or a numpy dtype.

  • time_step (uint32) – For applications that involve data along a time axis, this represents the point in time of the data. Defaults to 0.

  • user_id (uint32) – the id of the user. defaults to os.getuid()

  • app_name (str) – the name of the application. Defaults to an empty string.

Raises:

ValueError – if type is an unsupported numpy dtype, if dims is empty.

property app_name: unicode

The name of the application

copy() → Properties

Copy this properties object

Returns:

A copy of this object

property dims: Tuple[int, ...]

The dimensions of this object as a tuple.

property type: Type

The data type of this object. Can be set to a numpy dtype, but the output value of this property will be a Type instance.

property user_id: uint32

the id of the user.

class TransferRequest(*args)

Represents a transfer request to either set a region’s data or get it.

class RequestType(value)

The possible types of transfer request. Can be obtained with TransferRequest.type Either GET or SET.

property done: bool

True if this transfer request is completed

property result: Optional[ndarray[Any, dtype[ScalarType]]]

If the request is done and the request type is RequestType.GET, this is a numpy array containing the requested data. Otherwise, it is None.

wait()

Block until the result of the transfer request is available, then return it. If this is a GET request, the return value is the data, otherwise it is None.

property data: QueryComponent
An object used to build queries.
See Queries for more details.
delete()

Delete this Object. Do not access any methods or properties of this object after calling this.

property dims: Tuple[uint64, ...]

The dimensions of this object. read-only Equivalent to obj.get_properties().dims

classmethod get(name: unicode) → Object

Get an existing object by name

If you have created multiple objects with the same name, this will return the one with time_step=0 If there are multiple objects with the same name and time_step, the tie is broken arbitrarily

Parameters:

name (str) – the name of the object

get_data(region: Region = None) → TransferRequest

Request a region of data from an object

Parameters:

region (Region) – the region of data to get. If this is None, defaults to the entire object.

Returns:

A transfer request representing this request

Return type:

TransferRequest

property name: unicode

The name of this object. read-only

set_data(self, data, region: 'Region' = None)

Request a region of data from an object to be set to a new value

Parameters:

  • region (Region) – the region of data to set. Defaults to the entire object.

  • data – The data to set the region to. It must be a numpy array or convertible to a numpy array with numpy.array().

Returns:

A TransferRequest representing this request

Return type:

TransferRequest

property type: Type

The type of this object. read-only