---
title: "subscript(_:)"
framework: createml
role: symbol
role_heading: Instance Subscript
path: "createml/mldatatable/subscript(_:)-10r4l"
---

# subscript(_:)

Creates a subset of the table by masking the rows with the given untyped column.

## Declaration

```swift
subscript(mask: MLUntypedColumn) -> MLDataTable { get }
```

## Parameters

- `mask`: An untyped column indicating whether rows should be removed (a default value) or included (any nondefault value) in the derived table.

## Return Value

Return Value A new data table.

## Overview

Overview Use this untyped column–based subscript to create a new table by masking a subset of the table rows. The derived table will not include rows where mask contains a default value for its underlying type, such as: 0 in untyped Int columns 0.0 in untyped Double columns An empty string in untyped String columns The derived data table includes rows where the masking column has any other (nondefault) value.

For example, to filter the values in a data table as shown above, begin by creating a table with the original data. let data: [String: MLDataValueConvertible] = [     "Title": ["Alice in Wonderland", "Hamlet", "Dracula", "Peter Pan", "The Great Gatsby"],     "Genre": ["Fantasy", "Drama", "Adventure", "Fantasy", "Drama"],     "Pages": [124, 98, 0, 94, 0] ]

guard let table = try? MLDataTable(dictionary: data) else {     fatalError("Invalid dictionary data") } After you create the table, use the String-based subscript(_:) to extract a column. // Create a new untyped column "pagesColumn" copied from the table’s "Pages" column let pagesColumn = table["Pages"] Use subscript(mask: MLUntypedColumn) with an untyped column–row mask to create a filtered table. The subscript uses the untyped values to determine whether to keep a row. In this example, the untyped column pagesColumn has an underlying type of Int. The subscript removes any row with a value of 0 (the default value for Int) and keeps all other rows. // Filter the table using pagesColumn. // Each row with a value of 0 is removed. let validPageCountTable = table[pagesColumn]