can_cast

→bool

can_cast(from_: dtype, to: dtype)

source edit

Predicate: can from_ be cast to to under the promotion rules?

Returns True iff to's category is at least from_'s (bool $<$ int $<$ float $<$ complex). Casts within a category (both widening and narrowing, e.g. int8 → int32, int64 → int8, float64 → float32) and casts to a higher category are permitted; casts to a lower category (e.g. float32 → int32, complex64 → float32) are rejected.

Parameters

from_dtype-like

Source dtype.

todtype-like

Destination dtype.

Returns

bool

True if the cast is permitted, False otherwise.

Notes

With kind(d) denoting the category ordering bool < int < float < complex:

\operatorname{can\_cast}(\text{from},\;\text{to}) \;\iff\; \operatorname{kind}(\text{from}) \le \operatorname{kind}(\text{to}).

Contrast with result_type, which returns the target dtype for a mixed-type expression rather than a boolean — use can_cast for pre-flight checks, result_type for selecting an output dtype.

Examples

>>> import lucid
>>> lucid.can_cast(lucid.int8, lucid.int32)
True
>>> lucid.can_cast(lucid.float64, lucid.float32)
True
>>> lucid.can_cast(lucid.float32, lucid.int32)
False