Struct DataFrame 

pub struct DataFrame { /* private fields */ }

A columnar data structure. Each column is a named, typed array. All columns must have the same length.

Implementations

impl DataFrame

pub fn new(columns: Vec<Column>) -> Result<Self, DataFrameError>

Create a new DataFrame from columns. All columns must have the same length. Empty vec produces an empty DataFrame.

pub fn empty() -> Self

Create an empty DataFrame (no columns, no rows).

pub fn height(&self) -> usize

Number of rows.

pub fn width(&self) -> usize

Number of columns.

pub fn is_empty(&self) -> bool

Whether the DataFrame has no columns.

pub fn column(&self, name: &str) -> Result<&Column, DataFrameError>

Get a column by name.

pub fn column_names(&self) -> Vec<&str>

Get all column names.

pub fn columns(&self) -> &[Column]

Get all columns as a slice.

pub fn schema(&self) -> Schema

Get the schema (column names and types).

pub fn row(&self, index: usize) -> Option<Vec<Scalar>>

Get a row as a vector of Scalars.

pub fn with_column(&self, col: Column) -> Result<Self, DataFrameError>

Add or replace a column. If a column with the same name exists, it is replaced.

impl DataFrame

pub fn filter(&self, mask: &[bool]) -> Result<Self, DataFrameError>

Filter rows by a boolean mask. Mask length must equal height.

pub fn filter_by( &self, column: &str, predicate: impl Fn(&Scalar) -> bool, ) -> Result<Self, DataFrameError>

Filter rows by a predicate applied to a named column. Each row’s value is extracted as a Scalar and passed to the predicate.

impl DataFrame

pub fn group_by(&self, cols: &[&str]) -> Result<GroupBy<'_>, DataFrameError>

Group the DataFrame by specified columns. Returns a GroupBy that can be aggregated.

impl DataFrame

pub fn join( &self, other: &DataFrame, on: &[&str], how: JoinType, ) -> Result<DataFrame, DataFrameError>

Join two DataFrames on shared key column names.

Equivalent to self.join_on(other, on, on, how) — both tables use the same column names as join keys.

pub fn join_on( &self, other: &DataFrame, left_on: &[&str], right_on: &[&str], how: JoinType, ) -> Result<DataFrame, DataFrameError>

Join two DataFrames with potentially different key column names.

left_on columns from self, right_on columns from other. Key columns must have the same count. Column name collisions in non-key columns are resolved with _left / _right suffixes.

impl DataFrame

pub fn select(&self, names: &[&str]) -> Result<Self, DataFrameError>

Select a subset of columns by name. Returns an error if any column is not found.

pub fn drop_columns(&self, names: &[&str]) -> Self

Drop columns by name. Silently ignores names not found.

pub fn rename_column( &self, old: &str, new: &str, ) -> Result<Self, DataFrameError>

Rename a column. Returns error if the column is not found.

impl DataFrame

pub fn sort(&self, by: &str, descending: bool) -> Result<Self, DataFrameError>

Sort by a single column. Nulls sort last.

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

Take the first n rows.

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

Take the last n rows.

impl DataFrame

pub fn to_json(&self) -> Result<String, DataFrameError>

Serialize the DataFrame to a JSON string (array of row objects).

pub fn to_json_writer<W: Write>(&self, writer: W) -> Result<(), DataFrameError>

Serialize the DataFrame to a writer.

pub fn to_json_file(&self, path: &Path) -> Result<(), DataFrameError>

Write to a JSON file at the given path.

pub fn from_json(json: &str) -> Result<Self, DataFrameError>

Deserialize a DataFrame from a JSON string (array of row objects).

pub fn from_json_reader<R: Read>(reader: R) -> Result<Self, DataFrameError>

Deserialize a DataFrame from a reader.

Trait Implementations

impl Clone for DataFrame

fn clone(&self) -> DataFrame

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for DataFrame

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

Formats the value using the given formatter.

impl Display for DataFrame

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

Formats the value using the given formatter.