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Meta-learning via Language Model In-context Tuning

This is the implementation of the paper Meta-learning via Language Model In-context Tuning (to appear at ACL 2022).

Table of Contents

• Overview
• Requirements
• Code Structure
• Meta-training
• Meta-testing
• Demo
• How to Cite

Overview

In this work, we propose meta-learning via in-context tuning, which recasts the few-shot learning process of task adaptation and task-specific prediction as a simple sequence prediction problem, where few-shot labeled examples are concatenated with the target example to form the model input. In-context tuning out-performs a wide variety of baselines in terms of accuracy, including raw LM prompting, MAML and instruction tuning. Meanwhile, sensitivity study shows that our FSL approach of in-context tuning is significantly less sensitive to few-shot examples and instruction wording compared to raw LM prompting.

Given the empirical effectiveness of in-context tuning, we conjecture that the few-shot learning potential of large LMs (e.g., GPT-3) might be broadly underestimated, and that in-context tuning can eliminate well-known artifacts of few-shot LM prompting such as over-sensitivity to example ordering, example selection and instruction wording.

You could find more details of this work in our paper.

Requirements

To run our code, please install all the dependency packages by using the following command:

pip install -r requirements.txt

Code Structure

• ict.py includes code for in-context tuning (meta-training a model on various few-shot tasks → meta-testing few-shot learning on unseen tasks).

• data_loader.py includes code that samples few-shot in-context examples and embeds examples with natural language templates (prompts).

• verbalized_model.py includes code of a classification model that classifies examples by predicting the most likely class verbalizer (class labels are mapped one-on-one to class verbalizers).

Meta-training

To meta-train a model, please run the following command:

    python ict.py [--mode meta-train] [--model_name MODEL_NAME] [--task_format {mlm,clm}] [--device DEVICE] 
    [--task2examples TASK2EXAMPLES] [--task2templates TASK2TEMPLATES] [--task2verbalizers TASK2VERBALIZERS] 
    [--num_demonstrations NUM_DEMONSTRATIONS] [--example_delimiter EXAMPLE_DELIMITER] [--allow_label_overlap] 
    [--bsz BSZ] [--lr LR] [--num_warmup_steps NUM_WARMUP_STEPS] [--num_epochs NUM_EPOCHS] [--output_dir OUTPUT_DIR]

Here is the information of each argument to specify:

--mode meta-train: indicate you want to meta-train a model.

--model_name MODEL_NAME: name of the model.

--task_format {mlm,clm}: frame verbalizer classifcation as masked language modeling or causal language modeling.

--device DEVICE: device used for this experiment.

--task2examples TASK2EXAMPLES: path to the meta-training/meta-testing data file (a dictionary of task2examples).

--task2templates TASK2TEMPLATES: path to the meta-training/meta-testing templates file (a dictionary of task2templates).

--task2verbalizers TASK2VERBALIZERS: path to the meta-training/meta-testing verbalizers file (a dictionary of task2verbalizers).

--num_demonstrations NUM_DEMONSTRATIONS: number of few-shot demonstrations.

--example_delimiter EXAMPLE_DELIMITER: delimiter used to separate consecutive examples in the input text.

--allow_label_overlap: whether few-shot support examples are allowed to have overlapping labels with the query example.

--bsz BSZ: batch size for meta-training/meta-testing.

--lr LR: learning rate for meta-training.

--num_warmup_steps NUM_WARMUP_STEPS: number of warmup steps of the learning rate scheduler.

--num_epochs NUM_EPOCHS: number of meta-training epochs.

--output_dir OUTPUT_DIR: output directory to store the meta-trained model and the meta-training log file.

Meta-testing

To meta-test a meta-trained model, please run the following command:

    python ict.py [--mode meta-test] [--model_name MODEL_NAME] [--task_format {mlm,clm}] [--device DEVICE] 
    [--task2examples TASK2EXAMPLES] [--task2templates TASK2TEMPLATES] [--task2verbalizers TASK2VERBALIZERS] 
    [--num_demonstrations NUM_DEMONSTRATIONS] [--example_delimiter EXAMPLE_DELIMITER] [--allow_label_overlap] 
    [--bsz BSZ] [--num_prefix_selections NUM_PREFIX_SELECTIONS] [--load_model_path LOAD_MODEL_PATH]

Here is the information of each argument to specify:

--mode meta-test: indicate you want to meta-test a model.

--model_name MODEL_NAME: name of the model.

--task_format {mlm,clm}: frame verbalizer classifcation as masked language modeling or causal language modeling.

--device DEVICE: device used for this experiment.

--task2examples TASK2EXAMPLES: path to the meta-training/meta-testing data file (a dictionary of task2examples).

--task2templates TASK2TEMPLATES: path to the meta-training/meta-testing templates file (a dictionary of task2templates).

--task2verbalizers TASK2VERBALIZERS: path to the meta-training/meta-testing verbalizers file (a dictionary of task2verbalizers).

--num_demonstrations NUM_DEMONSTRATIONS: number of few-shot demonstrations.

--example_delimiter EXAMPLE_DELIMITER: delimiter used to separate consecutive examples in the input text.

--allow_label_overlap: whether few-shot support examples are allowed to have overlapping labels with the query example.

--bsz BSZ: batch size for meta-training/meta-testing.

--num_prefix_selections NUM_PREFIX_SELECTIONS: number of demonstration sampling for each query example (result averaged across different sampled demonstrations).

--load_model_path LOAD_MODEL_PATH: path to the meta-trained model to evaluate with.

Demo

As an example, we provide a code file src/example.py that can be run simply with cd src && python example.py

The code meta-trains a BERT-Base model on the training tasks of fold 0 of LAMA and meta-tests the meta-trained model on the validation and testing tasks of fold 0 of LAMA. Please refer to our paper for detailed information of the experiment.

Questions?

If you have any questions related to the code or the paper, feel free to reach out to us at yc3384@columbia.edu.

Citation

@inproceedings{chen-etal-2022-meta,
    title = "Meta-learning via Language Model In-context Tuning",
    author = "Chen, Yanda  and
      Zhong, Ruiqi  and
      Zha, Sheng  and
      Karypis, George  and
      He, He",
    booktitle = "Proceedings of the 60th Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers)",
    month = may,
    year = "2022",
    address = "Dublin, Ireland",
    publisher = "Association for Computational Linguistics",
    url = "https://aclanthology.org/2022.acl-long.53",
    doi = "10.18653/v1/2022.acl-long.53",
    pages = "719--730",
}