LengthBasedExampleSelector

Example:

from langchain_core.example_selectors import LengthBasedExampleSelector
from langchain_core.prompts import PromptTemplate

# Define examples
examples = [
    {"input": "happy", "output": "sad"},
    {"input": "tall", "output": "short"},
    {"input": "fast", "output": "slow"},
]

# Create prompt template
example_prompt = PromptTemplate(
    input_variables=["input", "output"],
    template="Input: {input}\nOutput: {output}",
)

# Create selector with max length constraint
selector = LengthBasedExampleSelector(
    examples=examples,
    example_prompt=example_prompt,
    max_length=50,  # Maximum prompt length
)

# Select examples for a new input
selected = selector.select_examples({"input": "large", "output": "tiny"})
# Returns examples that fit within max_length constraint