Add set.seed ability to CLI when splitting NLU data

[neelkes]

Description of Problem:
The user is not able to set a seed when using the CLI to split NLU data into test and training data sets (rasa split data nlu command). This feature will enhance reproducibility when required.

Overview of the Solution:
Add set.seed() to split_nlu_data.py or train_test_split.py

Definition of Done:

• Tests are added
• Feature described the docs
• Feature mentioned in the changelog

[sara-tagger]

Thanks for submitting this feature request 🚀@Ghostvv will get back to you about it soon!✨

Caw! 🐧

[tabergma]

Great idea 👍 We could add an argument like --random-seed to rasa split data nlu to set the seed. Needs to be added here: https://github.com/RasaHQ/rasa/blob/master/rasa/cli/data.py. And the seed should be forwarded to https://github.com/RasaHQ/rasa/blob/master/rasa/nlu/training_data/training_data.py#L400 in order to set it.

@neelkes Do you want to work on this feature yourself and submit a PR?

[joaorobson]

I found this enhancement pretty useful. Can I be assigned to this issue? (Supposing that @neelkes is not working with this feature anymore)

[tabergma]

@joaorobson Sure, feel free to work on it. Thanks! Let me know if you need help/if you have questions.