Trait LazyFileListReader

pub trait LazyFileListReader: Clone {
    // Required methods
    fn finish_no_glob(self) -> PolarsResult<LazyFrame>;
    fn sources(&self) -> &ScanSources;
    fn with_sources(self, source: ScanSources) -> Self;
    fn with_n_rows(self, n_rows: impl Into<Option<usize>>) -> Self;
    fn with_row_index(self, row_index: impl Into<Option<RowIndex>>) -> Self;
    fn rechunk(&self) -> bool;
    fn with_rechunk(self, toggle: bool) -> Self;
    fn n_rows(&self) -> Option<usize>;
    fn row_index(&self) -> Option<&RowIndex>;

    // Provided methods
    fn finish(self) -> PolarsResult<LazyFrame> { ... }
    fn concat_impl(&self, lfs: Vec<LazyFrame>) -> PolarsResult<LazyFrame> { ... }
    fn glob(&self) -> bool { ... }
    fn with_paths(self, paths: Arc<[PathBuf]>) -> Self { ... }
    fn cloud_options(&self) -> Option<&CloudOptions> { ... }
}

Reads LazyFrame from a filesystem or a cloud storage. Supports glob patterns.

Use LazyFileListReader::finish to get the final LazyFrame.

Required Methods

fn finish_no_glob(self) -> PolarsResult<LazyFrame>

Get the final LazyFrame. This method assumes, that path is not a glob.

It is recommended to always use LazyFileListReader::finish method.

fn sources(&self) -> &ScanSources

Get the sources for this reader.

fn with_sources(self, source: ScanSources) -> Self

Set sources of the scanned files.

fn with_n_rows(self, n_rows: impl Into<Option<usize>>) -> Self

Configure the row limit.

fn with_row_index(self, row_index: impl Into<Option<RowIndex>>) -> Self

Configure the row index.

fn rechunk(&self) -> bool

Rechunk the memory to contiguous chunks when parsing is done.

fn with_rechunk(self, toggle: bool) -> Self

Rechunk the memory to contiguous chunks when parsing is done.

fn n_rows(&self) -> Option<usize>

Try to stop parsing when n rows are parsed. During multithreaded parsing the upper bound n cannot be guaranteed.

fn row_index(&self) -> Option<&RowIndex>

Add a row index column.

Provided Methods

fn finish(self) -> PolarsResult<LazyFrame>

Get the final LazyFrame.

fn concat_impl(&self, lfs: Vec<LazyFrame>) -> PolarsResult<LazyFrame>

Recommended concatenation of LazyFrames from many input files.

This method should not take into consideration LazyFileListReader::n_rows nor LazyFileListReader::row_index.

fn glob(&self) -> bool

fn with_paths(self, paths: Arc<[PathBuf]>) -> Self

Set paths of the scanned files.

fn cloud_options(&self) -> Option<&CloudOptions>

CloudOptions used to list files.

Dyn Compatibility

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety", so this trait is not object safe.

Implementors

impl LazyFileListReader for LazyCsvReader

Available on crate feature csv only.

impl LazyFileListReader for LazyJsonLineReader

Available on crate feature json only.