---
title: validationData
framework: Create ML
role: symbol
role_heading: Instance Property
platforms: [macOS 10.15+]
path: createml/mlactivityclassifier/modelparameters-swift.struct/validationdata
---

# validationData

The activity classifier’s validation dataset.

## Declaration

```swift
var validationData: MLDataTable?
```

## Discussion

Discussion If you don’t specify validation data, the training process automatically sets aside a random subset of the training data as the validation data.

## See Also

### Accessing the training parameters

- [batchSize](createml/mlactivityclassifier/modelparameters-swift.struct/batchsize.md)
- [maximumIterations](createml/mlactivityclassifier/modelparameters-swift.struct/maximumiterations.md)
- [predictionWindowSize](createml/mlactivityclassifier/modelparameters-swift.struct/predictionwindowsize.md)
- [validation](createml/mlactivityclassifier/modelparameters-swift.struct/validation-swift.property.md)