Struct polars::prelude::LazyJsonLineReader

pub struct LazyJsonLineReader { /* private fields */ }

Available on crate feature lazy only.

Implementations

impl LazyJsonLineReader

pub fn new_paths(paths: Arc<[PathBuf]>) -> LazyJsonLineReader

pub fn new(path: impl AsRef<Path>) -> LazyJsonLineReader

pub fn with_row_index(self, row_index: Option<RowIndex>) -> LazyJsonLineReader

Add a row index column.

pub fn with_ignore_errors(self, ignore_errors: bool) -> LazyJsonLineReader

Set values as Null if parsing fails because of schema mismatches.

pub fn with_n_rows(self, num_rows: Option<usize>) -> LazyJsonLineReader

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

pub fn with_infer_schema_length( self, num_rows: Option<usize> ) -> LazyJsonLineReader

Set the number of rows to use when inferring the json schema. the default is 100 rows. Ignored when the schema is specified explicitly using Self::with_schema. Setting to None will do a full table scan, very slow.

pub fn with_schema(self, schema: Option<Arc<Schema>>) -> LazyJsonLineReader

Set the JSON file’s schema

pub fn low_memory(self, toggle: bool) -> LazyJsonLineReader

Reduce memory usage at the expense of performance

pub fn with_batch_size( self, batch_size: Option<NonZero<usize>> ) -> LazyJsonLineReader

Trait Implementations

impl AnonymousScan for LazyJsonLineReader

fn as_any(&self) -> &(dyn Any + 'static)

fn scan(&self, scan_opts: AnonymousScanArgs) -> Result<DataFrame, PolarsError>

Creates a DataFrame from the supplied function & scan options.

fn schema( &self, infer_schema_length: Option<usize> ) -> Result<Arc<Schema>, PolarsError>

function to supply the schema. Allows for an optional infer schema argument for data sources with dynamic schemas

fn allows_projection_pushdown(&self) -> bool

specify if the scan provider should allow projection pushdowns

fn allows_predicate_pushdown(&self) -> bool

specify if the scan provider should allow predicate pushdowns

fn allows_slice_pushdown(&self) -> bool

specify if the scan provider should allow slice pushdowns

impl Clone for LazyJsonLineReader

fn clone(&self) -> LazyJsonLineReader

Returns a copy of the value.

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

Performs copy-assignment from source.

impl LazyFileListReader for LazyJsonLineReader

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

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.

fn finish_no_glob(self) -> Result<LazyFrame, PolarsError>

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

fn path(&self) -> &Path

Path of the scanned file. It can be potentially a glob pattern.

fn paths(&self) -> &[PathBuf]

fn with_path(self, path: PathBuf) -> LazyJsonLineReader

Set path of the scanned file. Support glob patterns.

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

Set paths of the scanned files. Doesn’t glob patterns.

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

Configure the row limit.

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

Configure the row index.

fn rechunk(&self) -> bool

Rechunk the memory to contiguous chunks when parsing is done.

fn finish(self) -> Result<LazyFrame, PolarsError>

Get the final LazyFrame.

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

Recommended concatenation of LazyFrames from many input files.

fn glob(&self) -> bool

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

CloudOptions used to list files.

fn iter_paths( &self ) -> Result<Option<Box<dyn Iterator<Item = Result<PathBuf, PolarsError>>>>, PolarsError>

Get list of files referenced by this reader.