Enum Expr

pub enum Expr {
Show 27 variants    Element,
    Alias(Arc<Expr>, PlSmallStr),
    Column(PlSmallStr),
    Selector(Selector),
    Literal(LiteralValue),
    DataTypeFunction(DataTypeFunction),
    BinaryExpr {
        left: Arc<Expr>,
        op: Operator,
        right: Arc<Expr>,
    },
    Cast {
        expr: Arc<Expr>,
        dtype: DataTypeExpr,
        options: CastOptions,
    },
    Sort {
        expr: Arc<Expr>,
        options: SortOptions,
    },
    Gather {
        expr: Arc<Expr>,
        idx: Arc<Expr>,
        returns_scalar: bool,
        null_on_oob: bool,
    },
    SortBy {
        expr: Arc<Expr>,
        by: Vec<Expr>,
        sort_options: SortMultipleOptions,
    },
    Agg(AggExpr),
    Ternary {
        predicate: Arc<Expr>,
        truthy: Arc<Expr>,
        falsy: Arc<Expr>,
    },
    Function {
        input: Vec<Expr>,
        function: FunctionExpr,
    },
    Explode {
        input: Arc<Expr>,
        options: ExplodeOptions,
    },
    Filter {
        input: Arc<Expr>,
        by: Arc<Expr>,
    },
    Over {
        function: Arc<Expr>,
        partition_by: Vec<Expr>,
        order_by: Option<(Arc<Expr>, SortOptions)>,
        mapping: WindowMapping,
    },
    Rolling {
        function: Arc<Expr>,
        index_column: Arc<Expr>,
        period: Duration,
        offset: Duration,
        closed_window: ClosedWindow,
    },
    Slice {
        input: Arc<Expr>,
        offset: Arc<Expr>,
        length: Arc<Expr>,
    },
    KeepName(Arc<Expr>),
    Len,
    Field(Arc<[PlSmallStr]>),
    AnonymousFunction {
        input: Vec<Expr>,
        function: LazySerde<SpecialEq<Arc<dyn AnonymousColumnsUdf>>>,
        options: FunctionOptions,
        fmt_str: Box<PlSmallStr>,
    },
    Eval {
        expr: Arc<Expr>,
        evaluation: Arc<Expr>,
        variant: EvalVariant,
    },
    StructEval {
        expr: Arc<Expr>,
        evaluation: Vec<Expr>,
    },
    SubPlan(SpecialEq<Arc<DslPlan>>, Vec<String>),
    RenameAlias {
        function: RenameAliasFn,
        expr: Arc<Expr>,
    },
}

Expand description

Expressions that can be used in various contexts.

Queries consist of multiple expressions. When using the polars lazy API, don’t construct an Expr directly; instead, create one using the functions in the polars_lazy::dsl module. See that module’s docs for more info.

Variants§

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Element

Values in a eval context.

Equivalent of pl.element().

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BinaryExpr

Fields

§left: Arc<Expr>

§op: Operator

§right: Arc<Expr>

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Cast

Fields

§expr: Arc<Expr>

§dtype: DataTypeExpr

§options: CastOptions

§

Sort

Fields

§expr: Arc<Expr>

§options: SortOptions

§

Gather

Fields

§expr: Arc<Expr>

§idx: Arc<Expr>

§returns_scalar: bool

§null_on_oob: bool

§

SortBy

Fields

§expr: Arc<Expr>

§by: Vec<Expr>

§sort_options: SortMultipleOptions

§

Agg(AggExpr)

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Ternary

A ternary operation if true then “foo” else “bar”

Fields

§predicate: Arc<Expr>

§truthy: Arc<Expr>

§falsy: Arc<Expr>

§

Function

Fields

§input: Vec<Expr>

function arguments

§function: FunctionExpr

function to apply

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Explode

Fields

§input: Arc<Expr>

§options: ExplodeOptions

§

Filter

Fields

§input: Arc<Expr>

§by: Arc<Expr>

§

Over

Polars flavored window functions.

Fields

§function: Arc<Expr>

Also has the input. i.e. avg(“foo”)

§partition_by: Vec<Expr>

§order_by: Option<(Arc<Expr>, SortOptions)>

§mapping: WindowMapping

§

Rolling

Available on crate feature dynamic_group_by only.

Fields

§function: Arc<Expr>

§index_column: Arc<Expr>

§period: Duration

§offset: Duration

§closed_window: ClosedWindow

§

Slice

Fields

§input: Arc<Expr>

§offset: Arc<Expr>

length is not yet known so we accept negative offsets

§length: Arc<Expr>

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KeepName(Arc<Expr>)

Set root name as Alias

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Len

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Field(Arc<[PlSmallStr]>)

Available on crate feature dtype-struct only.

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AnonymousFunction

Fields

§input: Vec<Expr>

function arguments

§function: LazySerde<SpecialEq<Arc<dyn AnonymousColumnsUdf>>>

function to apply

§options: FunctionOptions

§fmt_str: Box<PlSmallStr>

used for formatting

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Eval

Evaluates the evaluation expression on the output of the expr.

Consequently, expr is an input and evaluation is not and needs a different schema.

Fields

§expr: Arc<Expr>

§evaluation: Arc<Expr>

§variant: EvalVariant

§

StructEval

Available on crate feature dtype-struct only.

Evaluates the evaluation expressions on the output of the expr.

Consequently, expr is an input and evaluation uses an extended schema that includes this input.

Fields

§expr: Arc<Expr>

§evaluation: Vec<Expr>

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SubPlan(SpecialEq<Arc<DslPlan>>, Vec<String>)

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RenameAlias

Fields

§function: RenameAliasFn

§expr: Arc<Expr>

Implementations§

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impl Expr

pub fn floor_div(self, rhs: Expr) -> Expr

Floor divide self by rhs.

pub fn pow<E>(self, exponent: E) -> Expr
where E: Into<Expr>,

Raise expression to the power exponent

pub fn sqrt(self) -> Expr

Compute the square root of the given expression