Datacat class

A versatile data structure resembling a DataFrame. It holds column names and rows of data and can optionally enforce a schema. It also provides static methods to create nested Datacats from JSON.

Constructors

Datacat({required List<String> columns, required List<List> rows})

Datacat.fromJsonString(String jsonString)

Creates a Datacat from a JSON string representing a list of objects.

factory

Datacat.withSchema({required DatacatSchema schema, required List<List> rows})

Creates a Datacat that enforces the provided schema. The columns are set to the keys from schema.requiredColumns. Throws an error if the provided rows do not conform.

Properties

columns ↔ List<String>

getter/setter pair

hashCode → int

The hash code for this object.

no setter, inherited

rows ↔ List<List>

getter/setter pair

runtimeType → Type

A representation of the runtime type of the object.

no setter, inherited

Methods

addRow(List row) → void

Adds a new row. Throws if the row length doesn't match columns.

describe() → Map<String, Map<String, num>>

Computes summary statistics for numeric columns. Returns a map mapping each numeric column to a map of count, sum, mean, min, and max.

dropColumns(List<String> dropColumns) → Datacat

Returns a new Datacat with the specified columns dropped.

fillNA(String columnName, dynamic fillValue) → Datacat

Fills missing (null) values in the specified column with fillValue.

groupBy(String columnName) → Map<dynamic, Datacat>

Groups rows by the given column and returns a Map from the group key to a Datacat.

head([int n = 5]) → Datacat

Returns a new Datacat containing the first n rows.

noSuchMethod(Invocation invocation) → dynamic

Invoked when a nonexistent method or property is accessed.

inherited

selectColumns(List<String> selectedColumns) → Datacat

Returns a new Datacat with only the selected columns.

sortBy(String columnName, {bool ascending = true}) → Datacat

Returns a new Datacat sorted by the given column.

tail([int n = 5]) → Datacat

Returns a new Datacat containing the last n rows.

toString() → String

A string representation of this object.

override

updateCell(int rowIndex, String columnName, dynamic newValue) → void

Updates a cell at rowIndex in column columnName with newValue.

Operators

operator ==(Object other) → bool

The equality operator.

inherited

Static Methods

fromJsonMapString(String jsonString) → Map<String, Datacat>

Creates nested Datacats from a JSON string representing a map, where each key maps to a list of objects. Returns a Map<String, Datacat>.