NdArray¶
- class nnabla.NdArray(*args, **kwargs)¶
nnabla.NdArray
is a device-agnostic data container for multi-dimensional arrays (tensors).nnabla.NdArray
can also implicitly handle data transfers across different devices (e.g. CPU to CUDA GPU, CUDA GPU to CPU). See Python API Tutorial for more details.NdArray
overrides some arithmetic operators (+
,-
,*
,/
,**
). Operands can be either a scalar number,NdArray
orVariable
. An arithmetic operation containingNdArray
returnsNdArray
which stores the output of the computation immediately invoked. Also, inplace arithmetic operations (+=
,-=
,*=
,/=
,**=
) are implemented. Note that=
doesn’t perform inplace substitution but just replaces the object reference. Instead, you can usecopy_from()
for inplace substitution.- cast(self, dtype, ctx=None)¶
In-place cast of data type of the NdArray. It returns the reference values as a numpy.ndarray only if optional parameter ctx is not given, None otherwise.
- Parameters
dtype (
numpy.dtype
) – Numpy Data type.ctx (
nnabla.Context
, optional) – Context descriptor.
- Returns
numpy.array
ifctx
is None, otherwise nothing.
- clear(self)¶
Clear memories which this NdArray has and return them to allocator.
- clear_called¶
Checking if the array is not modified after cleared. This returns False until clear is called at the first time.
- copy_from(self, NdArray arr, use_current_context=True)¶
Copy values from another NdArray object.
It returns the caller object itself.
- Parameters
arr (NdArray) – Values will be copied to the caller object. The shape of
arr`
must be same as the caller object.use_current_context (bool) – If True, a copy is happening in a device and dtype specified in the current context (equivalent to call
F.identity(src, output=[self])
). Otherwise, a device and dtype in the source array is used. The default is True.
- Returns
- data¶
Returns the values held by this array as a
numpy.ndarray
. Note that only the references are returned, and the values are not copied. Therefore, modifying the returnednnabla.NdArray
will affect the data contained inside the NNabla array. This method can also be called as a setter where an array is created as the same type as rhs. There is an exception wherezero()
orfill(rhs)
is invoked if a scalar with a float or an integer <= 2^53 (as filling value is maintained as float64) is given.Note that this may implicitly invoke a data transfer from device arrays to the CPU.
- Parameters
value (
numpy.ndarray
) –- Returns
- data_ptr(self, dtype, ctx=None)¶
Get array’s pointer.
The behavior is similar to
cast
method but returns the data pointer based on thectx
. If thectx
is not specified, the default context obtained bynn.get_current_context
is used.- Parameters
dtype (
numpy.dtype
) – Numpy Data type.ctx (
nnabla.Context
, optional) – Context descriptor.
- Returns
The data pointer.
- Return type
- dtype¶
Get dtype.
- Returns
- fill(self, value)¶
Fill all of the elements with the provided scalar value.
Note
This doesn’t not fill values in an internal array with 0 immediately. An array is created as a requested data type when this array is used (in forward or backward computation for exampe), and is filled with the value.
- Parameters
value (float) – The value filled with.
- static from_numpy_array(nparr)¶
Create a NdArray object from Numpy array data.
The data is initialized with the given Numpy array.
- Parameters
nparr (ndarray) – Numpy multi-dimensional array.
- Returns
nnabla.NdArray
- get_data(self, str mode='rw', dtype=None)¶
Returns the values held by this array as a
numpy.ndarray
with a specified mode.- Parameters
mode (str) – Computation becomes more efficient if right one is chosen. * ‘r’: Read-only access. * ‘w’: Write-only access. * ‘rw’: You can both read and write.
dtype (
numpy.dtype
, optional) – Force dtype of a returned array.
See :function:`nnabla.NdArray.data` for more details.
- modification_count¶
Returns how many times modified after memory allocation or clearing buffer.
- ndim¶
Number of dimensions.
- Returns
int
- shape¶
Shape of the N-d array.
- Returns
tuple of int
- size¶
Total size of the N-d array.
- Returns
int
- size_from_axis(self, axis=- 1)¶
Gets the size followed by the provided axis.
Example
a = nnabla.NdArray([10,9]) a.size_from_axis() # ==> 90 a.size_from_axis(0) # ==> 90 a.size_from_axis(1) # ==> 9 a.size_from_axis(2) # ==> 1
- strides¶
Strides.
- Returns
tuple of int
- zero(self)¶
Fill all of the elements with 0.
Note
This doesn’t not fill values in an internal array with 0 immediately. An array is created as a requested data type when this array is used (in forward or backward computation for exampe), and is filled with 0.