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# subscript(_:)

Creates a subset of the column by masking its elements with another
untyped column.

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

## Parameters

`mask`

An untyped column indicating whether elements should be removed
(a default value) or included (any nondefault value) in the derived
column.

## Return Value

A new column.

## Overview

Use this untyped column–based subscript to create a new column by
masking a subset of the elements. The derived column will not include
elements 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 column includes elements where the masking column has any
other (nondefault) value.

See [`subscript(_:)`](/documentation/CreateML/MLDataTable/subscript(_:)-10r4l) from [`MLDataTable`](/documentation/CreateML/MLDataTable) for an
example.

---

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