bench-answer-generator

name	bench-answer-generator
description	Reference documentation for the BenchAnswerGenerator operator. Covers the constructor, full run() signature, actual generation behavior, and integration notes for unified bench evaluation pipelines. Use when: generating model answers from benchmark question rows before passing the dataframe into UnifiedBenchDatasetEvaluator.
trigger_keywords	["BenchAnswerGenerator","bench-answer-generator","bench generation","answer generation","eval_type"]
version	1.0.0

BenchAnswerGenerator Operator Reference

BenchAnswerGenerator generates model answers from a benchmark dataframe and is designed to align with UnifiedBenchDatasetEvaluator.

1. Import

from dataflow.operators.core_text import BenchAnswerGenerator

2. Constructor

BenchAnswerGenerator(
    eval_type="key2_qa",
    llm_serving=llm,
    prompt_template=FormatStrPrompt(f_str_template="Question: {question}\nAnswer:"),
    system_prompt="You are a helpful assistant specialized in generating answers to questions.",
    allow_overwrite=False,
    force_generate=False,
)

Parameter	Required	Default	Description
eval_type	No	"key2_qa"	Evaluation type
llm_serving	Yes	None	LLM service object implementing generate_from_input(...)
prompt_template	No	FormatStrPrompt	Prompt object used to build prompts. In practice, pass a FormatStrPrompt(...) instance, None, or a DIYPromptABC subclass instance
system_prompt	No	"You are a helpful assistant specialized in generating answers to questions."	System prompt forwarded to the serving layer when supported
allow_overwrite	No	False	Whether to overwrite an existing output column
force_generate	No	False	Whether to force generation for some types that are skipped by default

Important prompt_template Note

Although the source code sets the default value to FormatStrPrompt, that default is the class object itself, not an instance.

In normal usage, you usually want to pass a FormatStrPrompt(...) instance so you can explicitly control the prompt text. None is also supported and makes the operator fall back to its built-in prompt builder.

Use one of these patterns instead:

from dataflow.prompts.core_text import FormatStrPrompt

prompt_template=FormatStrPrompt(
    f_str_template="Question: {question}\nAnswer:"
)

or

prompt_template=None

When prompt_template is a FormatStrPrompt instance, the current source may pass these fields into build_prompt(...):

• eval_type
• question
• context
• choices
• choices_text

For key2_qa and key2_q_ma, the practical required field is question. For key3_q_choices_a and key3_q_choices_as, the practical required fields are question and choices. If you want cleaner formatting for choice tasks, prefer {choices_text} over {choices}.

Supported eval_type Values

eval_type	Default behavior in current source
key1_text_score	Skips generation
key2_qa	Generates
key2_q_ma	Generates
key3_q_choices_a	Skips generation by default
key3_q_choices_as	Generates
key3_q_a_rejected	Skips generation

If force_generate=True, the current implementation generates for all types except key1_text_score.

3. run() Signature

op.run(
    storage=self.storage.step(),
    input_text_key=None,
    input_question_key=None,
    input_target_key=None,
    input_targets_key=None,
    input_choices_key=None,
    input_label_key=None,
    input_labels_key=None,
    input_better_key=None,
    input_rejected_key=None,
    input_context_key=None,
    output_key="generated_ans",
)
# returns: [output_key] or []

Parameter	Required	Default	Description
storage	Yes	None	Current operator-step storage object
input_text_key	No	None	Declared for evaluator API alignment; not used in current run() implementation
input_question_key	Conditionally required	None	Required whenever generation is actually performed
input_target_key	No	None	Declared for API alignment; not used in current run() implementation
input_targets_key	No	None	Declared for API alignment; not used in current run() implementation
input_choices_key	Conditionally required	None	Required for key3_q_choices_a and key3_q_choices_as when generation is performed
input_label_key	No	None	Declared for API alignment; not used in current run() implementation
input_labels_key	No	None	Declared for API alignment; not used in current run() implementation
input_better_key	No	None	Declared for API alignment; not used in current run() implementation
input_rejected_key	No	None	Declared for API alignment; not used in current run() implementation
input_context_key	No	None	Optional context column name
output_key	No	"generated_ans"	Output column written back into the dataframe

4. Actual Execution Logic

The current implementation behaves as follows:

1. Read the dataframe from storage.
2. Decide whether generation is needed by calling _need_generation(eval_type).
3. If generation is not needed, write the dataframe back unchanged and return [].
4. If output_key already exists and allow_overwrite=False, write the dataframe back unchanged and return [].
5. Require input_question_key to exist whenever generation is performed.
6. For key3_q_choices_a and key3_q_choices_as, also require input_choices_key.
7. If input_context_key is provided and exists, normalize it into a prompt context string.
8. Build one prompt per row using prompt_template.build_prompt(...) when available; otherwise fall back to an internal prompt template.
9. Call llm_serving.generate_from_input(...).
10. Write the generated answers into dataframe[output_key], persist via storage.write(df), and return [output_key].

5. Important Rules

1. In the current source, key3_q_choices_a does not generate by default. It is skipped unless force_generate=True.
2. In the current source, key1_text_score never generates, even if force_generate=True.
3. input_question_key is the only mandatory input column for generated question-answer flows in the current implementation.
4. The declared parameters input_text_key, input_target_key, input_targets_key, input_label_key, input_labels_key, input_better_key, and input_rejected_key are currently exposed for API compatibility, but they are not consumed inside run().
5. If input_choices_key is present but a row contains an empty or invalid value, the implementation substitutes [""] instead of failing that row.
6. The return value is a list: usually [output_key] on success, or [] when skipped.

6. Typical Usage

from dataflow.operators.core_text import BenchAnswerGenerator
from dataflow.prompts.core_text import FormatStrPrompt

prompt_template = FormatStrPrompt(
    f_str_template="Context: {context}\nQuestion: {question}\nAnswer:"
)

generator = BenchAnswerGenerator(
    eval_type="key2_qa",
    llm_serving=self.llm_serving,
    prompt_template=prompt_template,
    allow_overwrite=False,
)

generator.run(
    storage=self.storage.step(),
    input_question_key="question",
    input_context_key="context",
    output_key="generated_ans",
)