skbase.validate.is_sequence

skbase.validate.is_sequence(input_seq: Any, sequence_type: type | Tuple[type, ...] | None = None, element_type: type | Tuple[type, ...] | None = None) → bool

Indicate if an object is a sequence with optional check of element types.

If element_type is supplied all elements are also checked against provided types.

Parameters:

input_seqAny

The input sequence to be validated.

sequence_typetype or tuple[type, …], default=None

The allowed sequence type(s) that input_seq can be an instance of.

• If None, then collections.abc.Sequence is used (all sequence types are valid)

• If sequence_type is a type or tuple of types, then only the specified types are considered valid.

element_typetype or tuple[type], default=None

The allowed type(s) for elements of input_seq.

• If None, then the elements of input_seq are not checked when determining if input_seq is a valid sequence.

• If element_type is a type or tuple of types, then the elements of input_seq are checked to make sure they are all instances of the supplied element_type.

Returns:

bool

Whether the input is a valid sequence based on the supplied sequence_type and element_type.

Examples

>>> from skbase.base import BaseEstimator, BaseObject
>>> from skbase.validate import is_sequence
>>> is_sequence([1, 2, 3])
True
>>> is_sequence(7)
False

Generators are not sequences

>>> is_sequence((c for c in [1, 2, 3]))
False

The expected sequence type can be included in the check

>>> is_sequence([1, 2, 3, 4], sequence_type=list)
True
>>> is_sequence([1, 2, 3, 4], sequence_type=tuple)
False

The type of the elements can also be checked

>>> is_sequence([1, 2, 3], element_type=int)
True
>>> is_sequence([1, 2, 3, 4], sequence_type=list, element_type=int)
True
>>> is_sequence([1, 2, 3, 4], sequence_type=list, element_type=float)
False
>>> is_sequence([1, 2, 3, 4], sequence_type=list, element_type=(int, float))
True
>>> is_sequence((BaseObject(), BaseEstimator()), element_type=BaseObject)
True