Struct LazyFrame 

pub struct LazyFrame { /* private fields */ }

Lazy query API (LazyFrame, LazyGroupBy). A lazily-evaluated query backed by a LogicalPlan.

Implementations

impl LazyFrame

pub fn from_dataframe(df: DataFrame) -> Self

Create a LazyFrame that scans an in-memory DataFrame.

pub fn scan_csv(path: impl AsRef<Path>) -> Result<Self>

Build a CSV scan plan (no file I/O is performed until collect()).

pub fn scan_parquet(path: impl AsRef<Path>) -> Result<Self>

Build a Parquet scan plan (no file I/O is performed until collect()).

pub fn select(self, exprs: Vec<Expr>) -> Self

Add a projection (select) node to the logical plan.

pub fn filter(self, predicate: Expr) -> Self

Add a filter node to the logical plan.

pub fn with_columns(self, exprs: Vec<Expr>) -> Self

Add a projection (with_columns) node to the logical plan.

pub fn group_by(self, by: Vec<Expr>) -> LazyGroupBy

Start a group-by on this LazyFrame.

pub fn join<K: Into<JoinKeys>>( self, other: LazyFrame, keys: K, how: JoinType, ) -> Self

Join with another LazyFrame using provided join keys.

pub fn sort(self, options: SortOptions) -> Self

Sort by one or more columns.

pub fn head(self, n: usize) -> Self

Return the first n rows.

pub fn tail(self, n: usize) -> Self

Return the last n rows.

pub fn unique(self, subset: Option<Vec<String>>) -> Self

Remove duplicate rows.

pub fn fill_null<T: Into<FillNull>>(self, fill: T) -> Self

Fill null values using a scalar or strategy.

pub fn drop_nulls(self, subset: Option<Vec<String>>) -> Self

Drop rows containing null values.

pub fn null_count(self) -> Self

Count null values per column.

pub fn collect(self) -> Result<DataFrame>

Optimize, compile, and execute this LazyFrame into an eager DataFrame.

pub fn explain(self, optimized: bool) -> String

Render the logical plan as a human-readable string.

If optimized is true, includes optimizer rewrites such as pushdowns.

Trait Implementations

impl Clone for LazyFrame

fn clone(&self) -> LazyFrame

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for LazyFrame

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.