LazyGroupBy

Namespace: Polars.FSharp

A unified builder for Standard, Dynamic, and Rolling GroupBy operations. Holds the LazyFrame handle (ownership transferred to this builder) and grouping keys.

Constructors & Static Methods

new

new(lfHandle: LazyFrameHandle, groupByType: GroupByType, keys: Expr[]) : LazyGroupBy

Parameters

Name	Type	Description
lfHandle	LazyFrameHandle	-
groupByType	GroupByType	-
keys	Expr[]	-

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Instance Methods

Agg

Apply aggregations to the group. Routes the operation to the appropriate PolarsWrapper native call based on GroupByType.

member Agg(aggs: seq<Expr>) : LazyFrame
member Agg([<ParamArray>] aggs: Expr[]) : LazyFrame

Parameters

Name	Type	Description
aggs	seq<Expr> / Expr[]	-

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All

Aggregate all columns into lists.

member All : unit -> LazyFrame

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Count

Count the number of values in each group.

member Count : unit -> LazyFrame

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First

Aggregate the first values in the group.

member First(?ignoreNulls: bool) : LazyFrame

Parameters

Name	Type	Description
ignoreNulls	bool (optional)	-

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Having

Filter groups with a list of predicates after aggregation. Using this method is equivalent to adding the predicates to the aggregation and filtering afterwards.

member Having(predicate: Expr) : LazyGroupBy

Parameters

Name	Type	Description
predicate	Expr	-

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Head

Get the first n rows of each group.

member Head(?n: int) : LazyFrame

Parameters

Name	Type	Description
n	int (optional)	-

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Last

Aggregate the last values in the group.

member Last(?ignoreNulls: bool) : LazyFrame

Parameters

Name	Type	Description
ignoreNulls	bool (optional)	-

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Len

Return the number of rows in each group.

member Len(?name: string) : LazyFrame

Parameters

Name	Type	Description
name	string (optional)	-

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Max

Reduce the groups to the maximal value.

member Max : unit -> LazyFrame

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Mean

Reduce the groups to the mean value.

member Mean : unit -> LazyFrame

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Median

Reduce the groups to the median value.

member Median : unit -> LazyFrame

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Min

Reduce the groups to the minimal value.

member Min : unit -> LazyFrame

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NUnique

Count the unique values per group.

member NUnique : unit -> LazyFrame

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Quantile

Compute the quantile per group.

member Quantile(quantile: float, ?interpolation: QuantileMethod) : LazyFrame

Parameters

Name	Type	Description
quantile	float	-
interpolation	QuantileMethod (optional)	-

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Sum

Reduce the groups to the sum.

member Sum : unit -> LazyFrame

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Tail

Get the last n rows of each group.

member Tail(?n: int) : LazyFrame

Parameters

Name	Type	Description
n	int (optional)	-

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