Class: Table

An immutable table of named, equally long columns. Built by toTable (which every Express function calls on its data) or fromCSV.

Example

const t = toTable([
  { a: 1, b: 'x' },
  { a: 2, b: 'y' },
]);
t.names; // ['a', 'b']
t.column('a'); // [1, 2]
t.type('b'); // 'categorical'

Constructors

Constructor

new Table(columns): Table;

Parameters

Parameter	Type	Description
columns	| Record<string, readonly unknown[]> | ReadonlyMap<string, readonly unknown[]>	Columns by name; they must all have the same length.

Returns

Table

Throws

When columns differ in length.

Properties

Property	Modifier	Type	Description
length	readonly	number	Number of rows.
names	readonly	readonly string[]	Column names, in order.

Methods

column()

column(name): readonly unknown[];

The values of a column.

Parameters

Parameter	Type
name	string

Returns

readonly unknown[]

Throws

When there is no such column (the message lists the columns).

---

has()

has(name): boolean;

Whether the table has a column called name.

Parameters

Parameter	Type
name	string

Returns

boolean

---

toColumns()

toColumns(): Record<string, readonly unknown[]>;

The table as an object of columns (the arrays themselves, not copies).

Returns

Record<string, readonly unknown[]>

---

toRows()

toRows(): Record<string, unknown>[];

The table as row objects.

Returns

Record<string, unknown>[]

---

type()

type(name): ColumnType;

The inferred type of a column (see inferColumnType); computed once.

Parameters

Parameter	Type
name	string

Returns

ColumnType

---

withColumn()

withColumn(name, values): Table;

A new table with one more column (or a column replaced).

Parameters

Parameter	Type
name	string
values	readonly unknown[]

Returns

Table