VirtualLookupRange (Deedle) | Deedle

VirtualLookupRange Module

Namespace: Deedle.Virtual
Assembly: Deedle.dll

Helpers for configuring searchable columns on virtual sources.

Functions and values

Function or value	Description
`VirtualLookupRange.MaxInferredSearchCardinality` Full Usage: `VirtualLookupRange.MaxInferredSearchCardinality` Returns: `int`	Maximum distinct non-empty string values for automatic LookupRange inference. Inference scans the full column at load time and may build an IndexList map; this cap keeps that work bounded for enum-like columns and forces an explicit LookupRange mode (e.g. scan) when cardinality is high. Not tied to an existing Deedle constant — chosen as a conservative "small categorical" threshold (typical search columns ≪ 64; tests use ~100+ distinct as the high-cardinality case). Returns: `int`
`VirtualLookupRange.classifyLookupRange mode` Full Usage: `VirtualLookupRange.classifyLookupRange mode` Parameters: mode : `LookupRangeMode<'T>` Returns: `VirtualColumnLookupRange` Type parameters: 'T	Classify a configured [`LookupRangeMode`] for diagnostics (`Virtual.TryGetLookupRange`). mode : `LookupRangeMode<'T>` Returns: `VirtualColumnLookupRange`
`VirtualLookupRange.exactFixed selector` Full Usage: `VirtualLookupRange.exactFixed selector` Parameters: selector : `'T -> int64 * int64` Returns: `LookupRangeMode<'T>` Type parameters: 'T	selector : `'T -> int64 * int64` Returns: `LookupRangeMode<'T>`
`VirtualLookupRange.forCategorical indicesByValue` Full Usage: `VirtualLookupRange.forCategorical indicesByValue` Parameters: indicesByValue : `Map<'T, int64 list>` Returns: `LookupRangeMode<'T>` Type parameters: 'T (requires comparison)	IndexList LookupRange from a pre-built map of value -> row indices. indicesByValue : `Map<'T, int64 list>` Returns: `LookupRangeMode<'T>`
`VirtualLookupRange.forCategoricalScan length valueAt` Full Usage: `VirtualLookupRange.forCategoricalScan length valueAt` Parameters: length : `int64` valueAt : `int64 -> 'T` Returns: `LookupRangeMode<'T>` Type parameters: 'T (requires comparison)	Build categorical IndexList by scanning column values once at frame construction. length : `int64` valueAt : `int64 -> 'T` Returns: `LookupRangeMode<'T>`
`VirtualLookupRange.forCategoricalScanPresent length valueAt` Full Usage: `VirtualLookupRange.forCategoricalScanPresent length valueAt` Parameters: length : `int64` valueAt : `int64 -> 'T option` Returns: `LookupRangeMode<'T>` Type parameters: 'T (requires comparison)	Build categorical IndexList by scanning present (non-missing) values once at frame construction. length : `int64` valueAt : `int64 -> 'T option` Returns: `LookupRangeMode<'T>`
`VirtualLookupRange.forRepeatingCycle values` Full Usage: `VirtualLookupRange.forRepeatingCycle values` Parameters: values : `'T[]` Returns: `LookupRangeMode<'T>` Type parameters: 'T (requires equality)	Step LookupRange for values repeating on a fixed cycle (periodic categorical data). Unknown values yield an empty range (negative offset) instead of throwing. values : `'T[]` Returns: `LookupRangeMode<'T>`
`VirtualLookupRange.fullFixed` Full Usage: `VirtualLookupRange.fullFixed` Returns: `LookupRangeMode<'a>` Type parameters: 'a	Returns: `LookupRangeMode<'a>`
`VirtualLookupRange.resolveSearchColumnsLookupRange apiName searchColumns columnName columnKind inferStringValues inferInt64Values inferFloatValues` Full Usage: `VirtualLookupRange.resolveSearchColumnsLookupRange apiName searchColumns columnName columnKind inferStringValues inferInt64Values inferFloatValues` Parameters: apiName : `string` searchColumns : `VirtualSearchColumn list` columnName : `string` columnKind : `string` inferStringValues : `unit -> (LookupRangeMode<string> * string) option` inferInt64Values : `unit -> (LookupRangeMode<int64> * string) option` inferFloatValues : `unit -> (LookupRangeMode<float> * string) option` Returns: `ResolvedColumnSearch`	Resolve LookupRange for one column from [`VirtualReadCsvOptions.SearchColumns`] / Parquet equivalent. apiName : `string` searchColumns : `VirtualSearchColumn list` columnName : `string` columnKind : `string` inferStringValues : `unit -> (LookupRangeMode<string> * string) option` inferInt64Values : `unit -> (LookupRangeMode<int64> * string) option` inferFloatValues : `unit -> (LookupRangeMode<float> * string) option` Returns: `ResolvedColumnSearch`
`VirtualLookupRange.scan length valueAt` Full Usage: `VirtualLookupRange.scan length valueAt` Parameters: length : `int64` valueAt : `int64 -> 'T` Returns: `LookupRangeMode<'T>` Type parameters: 'T (requires equality)	Correct but O(N) per filter - scans all rows when LookupRange is invoked. length : `int64` valueAt : `int64 -> 'T` Returns: `LookupRangeMode<'T>`
`VirtualLookupRange.tryInferFloatLookupRange length valueAt` Full Usage: `VirtualLookupRange.tryInferFloatLookupRange length valueAt` Parameters: length : `int64` valueAt : `int64 -> float option` Returns: `(LookupRangeMode<float> * string) option`	Infer Step or categorical IndexList LookupRange for float columns (≤ [`MaxInferredSearchCardinality`] distinct present values). length : `int64` valueAt : `int64 -> float option` Returns: `(LookupRangeMode<float> * string) option`
`VirtualLookupRange.tryInferInt64LookupRange length valueAt` Full Usage: `VirtualLookupRange.tryInferInt64LookupRange length valueAt` Parameters: length : `int64` valueAt : `int64 -> int64 option` Returns: `(LookupRangeMode<int64> * string) option`	Infer Step or categorical IndexList LookupRange for int64 columns (≤ [`MaxInferredSearchCardinality`] distinct present values). length : `int64` valueAt : `int64 -> int64 option` Returns: `(LookupRangeMode<int64> * string) option`
`VirtualLookupRange.tryInferStringLookupRange length valueAt` Full Usage: `VirtualLookupRange.tryInferStringLookupRange length valueAt` Parameters: length : `int64` valueAt : `int64 -> string` Returns: `(LookupRangeMode<string> * string) option`	Infer Step or categorical IndexList LookupRange from column values (ReadCsv / ReadParquet). length : `int64` valueAt : `int64 -> string` Returns: `(LookupRangeMode<string> * string) option`