---
title: NDArray.InterleaveLayout
framework: coreai
role: symbol
role_heading: Structure
path: coreai/ndarray/interleavelayout-swift.struct
---

# NDArray.InterleaveLayout

Describes the interleaved memory layout of an ndArray dimension.

## Declaration

```swift
struct InterleaveLayout
```

## Overview

Overview An interleaved layout means that elements of the interleaved dimension are stored in physically contiguous blocks of factor elements (stride 1 between adjacent elements within a block). This differs from the standard layout where a dimension’s elements are separated by the strides of subsequent dimensions. A common use case is representing an image with interleaved channels: a [C, H, W] tensor uses InterleaveLayout(dimension: 0, factor: C) to store all channels for each pixel contiguously — like RGBRGB... — rather than in separate planar slices — like RRR...GGG...BBB.... More generally, this can be useful for optimizing the layout of an ndArray based on how the later compute will access it. Stride semantics The stride for the interleaved dimension (as reported by NDArray.strides) is a block stride — the distance in memory between adjacent blocks of factor elements, not between individual elements. Within a block, adjacent elements have stride 1. The element offset formula is: // Given strides and InterleaveLayout with dimension d and factor f: // offset = (index[d] / f) * strides[d] + (index[d] % f) //        + Σ index[i] * strides[i]  for all i ≠ d Equivalence with shape/stride transformations When factor divides the size of the interleaved dimension evenly, the layout can equivalently be expressed as a shape/stride transformation without interleave metadata. For example, for shape=[8, 256, 256] with InterleaveLayout(dimension: 0, factor: 4): // Interleaved representation: shape=[8, 256, 256], strides=[262144, 1024, 4] interleaveLayout=InterleaveLayout(dimension: 0, factor: 4)

// Equivalent shape/stride form (no interleave needed): shape=[2, 256, 256, 4], strides=[262144, 1024, 4, 1] interleaveLayout=nil The interleaved form preserves the original logical shape; the equivalent form makes the blocking explicit as an extra dimension. When factor does not divide the dimension size evenly, the shape/stride equivalence is not possible. In such case the interleaved representation is the only way to express the layout.

## Topics

### Initializers

- [init(dimension:factor:)](coreai/ndarray/interleavelayout-swift.struct/init(dimension:factor:).md)

### Instance Properties

- [dimension](coreai/ndarray/interleavelayout-swift.struct/dimension.md)
- [factor](coreai/ndarray/interleavelayout-swift.struct/factor.md)

## Relationships

### Conforms To

- [Equatable](swift/equatable.md)
- [Sendable](swift/sendable.md)
- [SendableMetatype](swift/sendablemetatype.md)