vllm/examples/offline_inference/encoder_decoder.py
Russell Bryant e489ad7a21
[Misc] Add SPDX-License-Identifier headers to python source files (#12628)
- **Add SPDX license headers to python source files**
- **Check for SPDX headers using pre-commit**

commit 9d7ef44c3cfb72ca4c32e1c677d99259d10d4745
Author: Russell Bryant <rbryant@redhat.com>
Date:   Fri Jan 31 14:18:24 2025 -0500

    Add SPDX license headers to python source files
    
This commit adds SPDX license headers to python source files as
recommended to
the project by the Linux Foundation. These headers provide a concise way
that is
both human and machine readable for communicating license information
for each
source file. It helps avoid any ambiguity about the license of the code
and can
    also be easily used by tools to help manage license compliance.
    
The Linux Foundation runs license scans against the codebase to help
ensure
    we are in compliance with the licenses of the code we use, including
dependencies. Having these headers in place helps that tool do its job.
    
    More information can be found on the SPDX site:
    
    - https://spdx.dev/learn/handling-license-info/
    
    Signed-off-by: Russell Bryant <rbryant@redhat.com>

commit 5a1cf1cb3b80759131c73f6a9dddebccac039dea
Author: Russell Bryant <rbryant@redhat.com>
Date:   Fri Jan 31 14:36:32 2025 -0500

    Check for SPDX headers using pre-commit
    
    Signed-off-by: Russell Bryant <rbryant@redhat.com>

---------

Signed-off-by: Russell Bryant <rbryant@redhat.com>
2025-02-02 11:58:18 -08:00

101 lines
3.3 KiB
Python

# SPDX-License-Identifier: Apache-2.0
'''
Demonstrate prompting of text-to-text
encoder/decoder models, specifically BART
'''
from vllm import LLM, SamplingParams
from vllm.inputs import (ExplicitEncoderDecoderPrompt, TextPrompt,
TokensPrompt, zip_enc_dec_prompts)
dtype = "float"
# Create a BART encoder/decoder model instance
llm = LLM(
model="facebook/bart-large-cnn",
dtype=dtype,
)
# Get BART tokenizer
tokenizer = llm.llm_engine.get_tokenizer_group()
# Test prompts
#
# This section shows all of the valid ways to prompt an
# encoder/decoder model.
#
# - Helpers for building prompts
text_prompt_raw = "Hello, my name is"
text_prompt = TextPrompt(prompt="The president of the United States is")
tokens_prompt = TokensPrompt(prompt_token_ids=tokenizer.encode(
prompt="The capital of France is"))
# - Pass a single prompt to encoder/decoder model
# (implicitly encoder input prompt);
# decoder input prompt is assumed to be None
single_text_prompt_raw = text_prompt_raw # Pass a string directly
single_text_prompt = text_prompt # Pass a TextPrompt
single_tokens_prompt = tokens_prompt # Pass a TokensPrompt
# - Pass explicit encoder and decoder input prompts within one data structure.
# Encoder and decoder prompts can both independently be text or tokens, with
# no requirement that they be the same prompt type. Some example prompt-type
# combinations are shown below, note that these are not exhaustive.
enc_dec_prompt1 = ExplicitEncoderDecoderPrompt(
# Pass encoder prompt string directly, &
# pass decoder prompt tokens
encoder_prompt=single_text_prompt_raw,
decoder_prompt=single_tokens_prompt,
)
enc_dec_prompt2 = ExplicitEncoderDecoderPrompt(
# Pass TextPrompt to encoder, and
# pass decoder prompt string directly
encoder_prompt=single_text_prompt,
decoder_prompt=single_text_prompt_raw,
)
enc_dec_prompt3 = ExplicitEncoderDecoderPrompt(
# Pass encoder prompt tokens directly, and
# pass TextPrompt to decoder
encoder_prompt=single_tokens_prompt,
decoder_prompt=single_text_prompt,
)
# - Finally, here's a useful helper function for zipping encoder and
# decoder prompts together into a list of ExplicitEncoderDecoderPrompt
# instances
zipped_prompt_list = zip_enc_dec_prompts(
['An encoder prompt', 'Another encoder prompt'],
['A decoder prompt', 'Another decoder prompt'])
# - Let's put all of the above example prompts together into one list
# which we will pass to the encoder/decoder LLM.
prompts = [
single_text_prompt_raw, single_text_prompt, single_tokens_prompt,
enc_dec_prompt1, enc_dec_prompt2, enc_dec_prompt3
] + zipped_prompt_list
print(prompts)
# Create a sampling params object.
sampling_params = SamplingParams(
temperature=0,
top_p=1.0,
min_tokens=0,
max_tokens=20,
)
# Generate output tokens from the prompts. The output is a list of
# RequestOutput objects that contain the prompt, generated
# text, and other information.
outputs = llm.generate(prompts, sampling_params)
# Print the outputs.
for output in outputs:
prompt = output.prompt
encoder_prompt = output.encoder_prompt
generated_text = output.outputs[0].text
print(f"Encoder prompt: {encoder_prompt!r}, "
f"Decoder prompt: {prompt!r}, "
f"Generated text: {generated_text!r}")