Miscellaneous

This page documents the miscellaneous members of the blosc2 module that do not fit into other categories.

blosc2.DEFAULT_COMPLEX

Default complex floating dtype.

Attributes:
T

Scalar attribute identical to the corresponding array attribute.

base

Scalar attribute identical to the corresponding array attribute.

data

Pointer to start of data.

device
dtype

Get array data-descriptor.

flags

The integer value of flags.

flat

A 1-D view of the scalar.

itemset
itemsize

The length of one element in bytes.

nbytes
ndim

The number of array dimensions.

newbyteorder
ptp
shape

Tuple of array dimensions.

size

The number of elements in the gentype.

strides

Tuple of bytes steps in each dimension.

Methods

trace

program/module to trace Python program or function execution

to_device

tobytes
blosc2.DEFAULT_FLOAT

Default real floating dtype.

Attributes:
T

Scalar attribute identical to the corresponding array attribute.

base

Scalar attribute identical to the corresponding array attribute.

data

Pointer to start of data.

device
dtype

Get array data-descriptor.

flags

The integer value of flags.

flat

A 1-D view of the scalar.

itemset
itemsize

The length of one element in bytes.

nbytes
ndim

The number of array dimensions.

newbyteorder
ptp
shape

Tuple of array dimensions.

size

The number of elements in the gentype.

strides

Tuple of bytes steps in each dimension.

Methods

trace

program/module to trace Python program or function execution

to_device

tobytes
blosc2.DEFAULT_INDEX

Default indexing dtype.

Attributes:
T

Scalar attribute identical to the corresponding array attribute.

base

Scalar attribute identical to the corresponding array attribute.

data

Pointer to start of data.

denominator

denominator of value (1)

device
dtype

Get array data-descriptor.

flags

The integer value of flags.

flat

A 1-D view of the scalar.

itemset
itemsize

The length of one element in bytes.

nbytes
ndim

The number of array dimensions.

newbyteorder
numerator

numerator of value (the value itself)

ptp
shape

Tuple of array dimensions.

size

The number of elements in the gentype.

strides

Tuple of bytes steps in each dimension.

Methods

trace

program/module to trace Python program or function execution

to_device

tobytes
blosc2.DEFAULT_INT

Default integer dtype.

Attributes:
T

Scalar attribute identical to the corresponding array attribute.

base

Scalar attribute identical to the corresponding array attribute.

data

Pointer to start of data.

denominator

denominator of value (1)

device
dtype

Get array data-descriptor.

flags

The integer value of flags.

flat

A 1-D view of the scalar.

itemset
itemsize

The length of one element in bytes.

nbytes
ndim

The number of array dimensions.

newbyteorder
numerator

numerator of value (the value itself)

ptp
shape

Tuple of array dimensions.

size

The number of elements in the gentype.

strides

Tuple of bytes steps in each dimension.

Methods

trace

program/module to trace Python program or function execution

to_device

tobytes
class blosc2.Operand[source]

Base class for all operands in expressions.

Attributes:
device

Hardware device the array data resides on.

dtype

Get the data type of the Operand.

info

Get information about the Operand.

ndim

Get the number of dimensions of the Operand.

shape

Get the shape of the Operand.

Methods

argmax([axis, keepdims])

Returns the indices of the maximum values along a specified axis.

argmin([axis, keepdims])

Returns the indices of the minimum values along a specified axis.

item()

Copy an element of an array to a standard Python scalar and return it.

to_device(device)

Copy the array from the device on which it currently resides to the specified device.
argmax(axis=None, keepdims=False, **kwargs)[source]

Returns the indices of the maximum values along a specified axis.

When the maximum value occurs multiple times, only the indices corresponding to the first occurrence are returned.

Parameters:

  • x (blosc2.Array) – Input array. Should have a real-valued data type.

  • axis (int | None) – Axis along which to search. If None, return index of the maximum value of flattened array. Default: None.

  • keepdims (bool) – If True, reduced axis included in the result as singleton dimension. Otherwise, axis not included in the result. Default: False.

Returns:

out – If axis is None, a zero-dimensional array containing the index of the first occurrence of the maximum value; otherwise, a non-zero-dimensional array containing the indices of the maximum values.

Return type:

blosc2.Array

argmin(axis=None, keepdims=False, **kwargs)[source]

Returns the indices of the minimum values along a specified axis.

When the minimum value occurs multiple times, only the indices corresponding to the first occurrence are returned.

Parameters:

  • x (blosc2.Array) – Input array. Should have a real-valued data type.

  • axis (int | None) – Axis along which to search. If None, return index of the minimum value of flattened array. Default: None.

  • keepdims (bool) – If True, reduced axis included in the result as singleton dimension. Otherwise, axis not included in the result. Default: False.

Returns:

out – If axis is None, a zero-dimensional array containing the index of the first occurrence of the minimum value; otherwise, a non-zero-dimensional array containing the indices of the minimum values.

Return type:

blosc2.Array

property device

Hardware device the array data resides on. Always equal to ‘cpu’.

abstract property dtype: dtype

Get the data type of the Operand.

Returns:

out – The data type of the Operand.

Return type:

np.dtype

abstract property info: InfoReporter

Get information about the Operand.

Returns:

out – A printable class with information about the Operand.

Return type:

InfoReporter

item() → float | bool | complex | int[source]

Copy an element of an array to a standard Python scalar and return it.

abstract property ndim: int

Get the number of dimensions of the Operand.

Returns:

out – The number of dimensions of the Operand.

Return type:

int

abstract property shape: tuple[int]

Get the shape of the Operand.

Returns:

out – The shape of the Operand.

Return type:

tuple

to_device(device: str)[source]

Copy the array from the device on which it currently resides to the specified device.

Parameters:

  • self (NDArray) – Array instance.

  • device (str) – Device to move array object to. Returns error except when device==’cpu’.

Returns:

out – If device=’cpu’, the same array; else raises an Error.

Return type:

NDArray

class blosc2.ProxyNDField(proxy: Proxy, field: str)[source]
Attributes:
device

Hardware device the array data resides on.

dtype

Get the data type of the ProxyNDField.

info

Get information about the Operand.

ndim

Get the number of dimensions of the Operand.

shape

Get the shape of the ProxyNDField.

Methods

argmax([axis, keepdims])

Returns the indices of the maximum values along a specified axis.

argmin([axis, keepdims])

Returns the indices of the minimum values along a specified axis.

item()

Copy an element of an array to a standard Python scalar and return it.

to_device(device)

Copy the array from the device on which it currently resides to the specified device.
property dtype: dtype

Get the data type of the ProxyNDField.

Returns:

out – The data type of the ProxyNDField.

Return type:

np.dtype

property shape: tuple[int]

Get the shape of the ProxyNDField.

Returns:

out – The shape of the ProxyNDField.

Return type:

tuple

blosc2.array_from_ffi_ptr(array_ptr) → NDArray[source]

Create an NDArray from a raw FFI pointer.

This function is useful for passing arrays across FFI boundaries. This function move the ownership of the underlying b2nd_array_t* object to the new NDArray, and it will be freed when the object is destroyed.

blosc2.as_simpleproxy(*arrs: Sequence[Array]) → tuple[SimpleProxy | Operand][source]

Convert an Array object which fulfills Array protocol into SimpleProxy. If x is already a blosc2.Operand simply returns object.

Parameters:

arrs (Sequence[blosc2.Array]) – Objects fulfilling Array protocol.

Returns:

out – Objects with minimal interface for blosc2 LazyExpr computations.

Return type:

tuple[blosc2.SimpleProxy | blosc2.Operand]

class blosc2.finfo(dtype)

Machine limits for floating point types.

bits

The number of bits occupied by the type.

Type:

int

dtype

Returns the dtype for which finfo returns information. For complex input, the returned dtype is the associated float* dtype for its real and complex components.

Type:

dtype

eps

The difference between 1.0 and the next smallest representable float larger than 1.0. For example, for 64-bit binary floats in the IEEE-754 standard, eps = 2**-52, approximately 2.22e-16.

Type:

float

epsneg

The difference between 1.0 and the next smallest representable float less than 1.0. For example, for 64-bit binary floats in the IEEE-754 standard, epsneg = 2**-53, approximately 1.11e-16.

Type:

float

iexp

The number of bits in the exponent portion of the floating point representation.

Type:

int

machep

The exponent that yields eps.

Type:

int

max

The largest representable number.

Type:

floating point number of the appropriate type

maxexp

The smallest positive power of the base (2) that causes overflow.

Type:

int

min

The smallest representable number, typically -max.

Type:

floating point number of the appropriate type

minexp

The most negative power of the base (2) consistent with there being no leading 0’s in the mantissa.

Type:

int

negep

The exponent that yields epsneg.

Type:

int

nexp

The number of bits in the exponent including its sign and bias.

Type:

int

nmant

The number of bits in the mantissa.

Type:

int

precision

The approximate number of decimal digits to which this kind of float is precise.

Type:

int

resolution

The approximate decimal resolution of this type, i.e., 10**-precision.

Type:

floating point number of the appropriate type

tiny

An alias for smallest_normal, kept for backwards compatibility.

Type:

float

smallest_normal

The smallest positive floating point number with 1 as leading bit in the mantissa following IEEE-754 (see Notes).

Type:

float

smallest_subnormal

The smallest positive floating point number with 0 as leading bit in the mantissa following IEEE-754.

Type:

float

Parameters:

dtype (float, dtype, or instance) – Kind of floating point or complex floating point data-type about which to get information.

See also

iinfo

The equivalent for integer data types.

spacing

The distance between a value and the nearest adjacent number

nextafter

The next floating point value after x1 towards x2

Notes

For developers of NumPy: do not instantiate this at the module level. The initial calculation of these parameters is expensive and negatively impacts import times. These objects are cached, so calling finfo() repeatedly inside your functions is not a problem.

Note that smallest_normal is not actually the smallest positive representable value in a NumPy floating point type. As in the IEEE-754 standard [1], NumPy floating point types make use of subnormal numbers to fill the gap between 0 and smallest_normal. However, subnormal numbers may have significantly reduced precision [2].

This function can also be used for complex data types as well. If used, the output will be the same as the corresponding real float type (e.g. numpy.finfo(numpy.csingle) is the same as numpy.finfo(numpy.single)). However, the output is true for the real and imaginary components.

References

[1]

IEEE Standard for Floating-Point Arithmetic, IEEE Std 754-2008, pp.1-70, 2008, https://doi.org/10.1109/IEEESTD.2008.4610935

[2]

Wikipedia, “Denormal Numbers”, https://en.wikipedia.org/wiki/Denormal_number

Examples

>>> import numpy as np
>>> np.finfo(np.float64).dtype
dtype('float64')
>>> np.finfo(np.complex64).dtype
dtype('float32')
Attributes:
smallest_normal

Return the value for the smallest normal.

tiny

Return the value for tiny, alias of smallest_normal.

property smallest_normal

Return the value for the smallest normal.

Returns:

smallest_normal – Value for the smallest normal.

Return type:

float

Warns:

UserWarning – If the calculated value for the smallest normal is requested for double-double.

property tiny

Return the value for tiny, alias of smallest_normal.

Returns:

tiny – Value for the smallest normal, alias of smallest_normal.

Return type:

float

Warns:

UserWarning – If the calculated value for the smallest normal is requested for double-double.

class blosc2.iinfo(type)

Machine limits for integer types.

bits

The number of bits occupied by the type.

Type:

int

dtype

Returns the dtype for which iinfo returns information.

Type:

dtype

min

The smallest integer expressible by the type.

Type:

int

max

The largest integer expressible by the type.

Type:

int

Parameters:

int_type (integer type, dtype, or instance) – The kind of integer data type to get information about.

See also

finfo

The equivalent for floating point data types.

Examples

With types:

>>> import numpy as np
>>> ii16 = np.iinfo(np.int16)
>>> ii16.min
-32768
>>> ii16.max
32767
>>> ii32 = np.iinfo(np.int32)
>>> ii32.min
-2147483648
>>> ii32.max
2147483647

With instances:

>>> ii32 = np.iinfo(np.int32(10))
>>> ii32.min
-2147483648
>>> ii32.max
2147483647