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Text Generation

Thanks to the base Transformers package, aitextgen has more options for generating text than other text-generating apps before.

Generation Parameters

See this article by Huggingface engineer Patrick von Platen for how sampling and these parameters are used in practice.

  • n: Number of texts generated.
  • max_length: Maximum length of the generated text (default: 200; for GPT-2, the maximum is 1024; for GPT Neo, the maximum is 2048)
  • prompt: Prompt that starts the generated text and is included in the generated text.
  • temperature: Controls the "craziness" of the text (default: 0.7)
  • top_k: If nonzero, limits the sampled tokens to the top k values. (default: 0)
  • top_p: If nonzero, limits the sampled tokens to the cumulative probability

Some lesser-known-but-still-useful-parameters that are unique to Transformers:


Enabling these parameters may slow down generation.

  • num_beams: If greater than 1, executes beam search for cleaner text.
  • repetition_penalty: If greater than 1.0, penalizes repetition in a text to avoid infinite loops.
  • length_penalty: If greater than 1.0, penalizes text proportional to the length
  • no_repeat_ngram_size: Token length to avoid repeating given phrases.

Generation Functions

Given a aitextgen object with a loaded model + tokenizer named ai:

About devices

aitextgen does not automatically set the device used to generate text. If you want to generate on the GPU, make sure you call ai.to_gpu() beforehand, or load the model into the GPU using ai = aitextgen(to_gpu=True)

  • ai.generate(): Generates and prints text to console. If prompt is used, the prompt is bolded.
  • ai.generate_one(): A helper function which generates a single text and returns as a string (good for APIs)
  • ai.generate_samples(): Generates multiple samples at specified temperatures: great for debugging.
  • ai.generate_to_file(): Generates a bulk amount of texts to file. (this accepts a batch_size parameter which is useful if using on a GPU, as it can generate texts in parallel with no performance loss)

lstrip and nonempty_output

By default, the lstrip and nonempty_output parameters to generate are set to True, which alters the behavior of the generated text in a way that is most likely preferable. lstrip: Removes all whitespace at the beginning of the generated space. nonempty_output: If the output is empty (possible on shortform content), skip it if generating multiple texts, or try again if it's a single text. If min_length is specified, the same behavior occurs for texts below the minimum length after processing.


aitextgen has a new seed parameter for generation. Using any generate function with a seed parameter (must be an integer) and all other models/parameters the same, and the generated text will be identical. This allows for reproducible generations in case someone accuses you of faking the AI output.

For generate_to_file(), the 8-digit number at the end of the file name will be the seed used to generate the file, making reprodicibility easy.