Few-shot prompt templates in LangChain - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a few-shot prompt template with examples.

LangChain

from langchain.prompts import FewShotPromptTemplate, PromptTemplate

example_prompt = PromptTemplate(input_variables=["word"], template="Translate '{{word}}' to French: '[1]'")

examples = [{"word": "hello", "translation": "bonjour"}]

few_shot_prompt = FewShotPromptTemplate(
    examples=examples,
    example_prompt=example_prompt,
    input_variables=["word"]
)

Drag options to blanks, or click blank then click option'

Atranslation

Bbonjour

Chello

Dword

Attempts:

3 left

💡 Hint

Common Mistakes

Using the input variable 'word' instead of the output variable 'translation' in the template.

Confusing the example keys with input variables.

The example prompt template uses 'translation' as the variable to fill the French word in the template.

2fill in blank

medium

Complete the code to set the prefix for the few-shot prompt template.

LangChain

few_shot_prompt = FewShotPromptTemplate(
    examples=examples,
    example_prompt=example_prompt,
    prefix=[1],
    input_variables=["word"]
)

Drag options to blanks, or click blank then click option'

ATranslate English to French

BTranslate English to French:

C'Translate English to French:'

D"Translate English to French:"

Attempts:

3 left

💡 Hint

Common Mistakes

Forgetting to put quotes around the prefix string.

Using single quotes inconsistently.

The prefix must be a string literal, so it needs to be enclosed in quotes.

3fill in blank

hard

Fix the error in the code to correctly create a few-shot prompt template with suffix.

LangChain

few_shot_prompt = FewShotPromptTemplate(
    examples=examples,
    example_prompt=example_prompt,
    prefix="Translate English to French:",
    suffix=[1],
    input_variables=["word"]
)

Drag options to blanks, or click blank then click option'

A"Input: {word}\nOutput:"

BInput: {word}\nOutput:

C'Input: {word}\nOutput:'

DInput: {word} Output:

Attempts:

3 left

💡 Hint

Common Mistakes

Not using quotes around the suffix string.

Not escaping the newline character properly.

The suffix must be a string literal with placeholders, so it needs to be enclosed in quotes and use proper escape sequences.

4fill in blank

hard

Fill both blanks to create a few-shot prompt template with example separator and suffix.

LangChain

few_shot_prompt = FewShotPromptTemplate(
    examples=examples,
    example_prompt=example_prompt,
    example_separator=[1],
    suffix=[2],
    input_variables=["word"]
)

Drag options to blanks, or click blank then click option'

A"\n---\n"

B"\n"

C"Input: {word}\nOutput:"

D"\n\n"

Attempts:

3 left

💡 Hint

Common Mistakes

Using incorrect separator strings without newlines.

Not including the input variable placeholder in the suffix.

The example separator is a string with newlines and dashes, and the suffix includes the input variable placeholder.

5fill in blank

hard

Fill all three blanks to build a few-shot prompt template with prefix, example separator, and suffix.

LangChain

few_shot_prompt = FewShotPromptTemplate(
    examples=examples,
    example_prompt=example_prompt,
    prefix=[1],
    example_separator=[2],
    suffix=[3],
    input_variables=["word"]
)

Drag options to blanks, or click blank then click option'

A"Translate English to French:"

B"\n---\n"

C"Input: {word}\nOutput:"

D"Please translate the following words:"

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up prefix and suffix strings.

Not using proper escape sequences in separator and suffix.

The prefix is a polite instruction, the example separator uses newlines and dashes, and the suffix prompts for input and output.

Practice

1. What is the main purpose of a few-shot prompt template in Langchain?

easy

A. To provide example prompts and responses to guide AI behavior

B. To store large datasets for training AI models

C. To execute code on the AI server

D. To create user interfaces for AI applications

Solution

1. Step 1: Understand few-shot prompt templates

   Few-shot prompt templates include example prompts and responses to teach AI how to answer.

2. Step 2: Identify the main purpose

   The main goal is to guide AI behavior by showing examples, not to store data or create interfaces.

3. Final Answer:

   To provide example prompts and responses to guide AI behavior -> Option A

4. Quick Check:

   Few-shot prompt templates guide AI with examples = A [OK]

Hint: Remember: few-shot means showing examples to teach AI [OK]

Common Mistakes:

• Confusing prompt templates with data storage
• Thinking they run code instead of guiding AI
• Assuming they build UI components

2. Which of the following is the correct way to create a few-shot prompt template in Langchain?

easy

A. FewShotPromptTemplate(data=examples, prompt=example_prompt, suffix=prefix_text)

B. FewShotPromptTemplate(samples=examples, prompt_template=example_prompt, header=prefix_text)

C. FewShotPromptTemplate(examples=examples, example_prompt=example_prompt, prefix=prefix_text)

D. FewShotPromptTemplate(inputs=examples, prompt=example_prompt, footer=prefix_text)

Solution

1. Step 1: Recall Langchain few-shot prompt syntax

   The correct constructor uses parameters: examples, example_prompt, and prefix.

2. Step 2: Match parameters to options

   Only FewShotPromptTemplate(examples=examples, example_prompt=example_prompt, prefix=prefix_text) uses the exact parameter names required by Langchain's FewShotPromptTemplate.

3. Final Answer:

   FewShotPromptTemplate(examples=examples, example_prompt=example_prompt, prefix=prefix_text) -> Option C

4. Quick Check:

   Correct parameter names = B [OK]

Hint: Check parameter names exactly as in Langchain docs [OK]

Common Mistakes:

• Using wrong parameter names like data or samples
• Mixing prefix with suffix or footer
• Confusing example_prompt with prompt_template

3. Given this code snippet, what will be the output of print(prompt_template.format(input="Translate to French: Hello") )?

examples = [{"input": "Hello", "output": "Bonjour"}]
example_prompt = PromptTemplate(input_variables=["input", "output"], template="Input: {input}\nOutput: {output}")
prompt_template = FewShotPromptTemplate(examples=examples, example_prompt=example_prompt, prefix="Translate English to French:\n", suffix="\nInput: {input}\nOutput:", input_variables=["input"])

medium

A. Translate English to French:
Input: Translate to French: Hello
Output:

B. Translate English to French:
Input: Hello
Output: Bonjour
Translate to French: Hello

C. Input: Hello
Output: Bonjour
Translate English to French: Hello

D. Translate English to French:
Input: Hello
Output: Bonjour
Input: Translate to French: Hello
Output:

Solution

1. Step 1: Understand few-shot prompt formatting

   The prompt includes the prefix, then example prompts formatted with example data, then the new input prompt.

2. Step 2: Apply formatting to given input

   The prefix is "Translate English to French:", then example "Input: Hello\nOutput: Bonjour", then the new input "Input: Translate to French: Hello\nOutput:" (empty output to be filled by AI).

3. Final Answer:

   Translate English to French: Input: Hello Output: Bonjour Input: Translate to French: Hello Output: -> Option D

4. Quick Check:

   Prefix + example + new input prompt = C [OK]

Hint: Few-shot templates show prefix, examples, then new input [OK]

Common Mistakes:

• Ignoring prefix text in output
• Not formatting new input as 'Input: ... Output:'
• Confusing example data with new input

4. What is the error in this code snippet that tries to create a few-shot prompt template?

examples = [{"input": "Hi", "output": "Salut"}]
example_prompt = PromptTemplate(input_variables=["input", "output"], template="Input: {input}\nOutput: {output}")
prompt_template = FewShotPromptTemplate(examples=examples, example_prompt=example_prompt, prefix="Translate:")
print(prompt_template.format(input="Hello"))

medium

A. PromptTemplate cannot have input_variables

B. Missing input_variables parameter in FewShotPromptTemplate constructor

C. Prefix must be a function, not a string

D. examples list should be empty for FewShotPromptTemplate

Solution

1. Step 1: Check FewShotPromptTemplate required parameters

   FewShotPromptTemplate requires input_variables parameter to know which inputs to expect.

2. Step 2: Identify missing parameter

   The code misses input_variables in FewShotPromptTemplate, causing an error when calling format.

3. Final Answer:

   Missing input_variables parameter in FewShotPromptTemplate constructor -> Option B

4. Quick Check:

   input_variables missing = D [OK]

Hint: Always include input_variables when creating prompt templates [OK]

Common Mistakes:

• Omitting input_variables in FewShotPromptTemplate
• Thinking prefix must be a function
• Assuming examples can be empty

5. You want to create a few-shot prompt template that filters out examples with empty outputs before formatting. Which approach correctly applies this filtering in Langchain?

hard

A. Filter the examples list before passing it to FewShotPromptTemplate constructor

B. Use a custom example_prompt that skips empty outputs during formatting

C. Set prefix to None and rely on Langchain to ignore empty outputs

D. Pass all examples and filter outputs after calling prompt_template.format()

Solution

1. Step 1: Understand filtering in few-shot templates

   FewShotPromptTemplate uses the examples list as-is; filtering must happen before passing examples.

2. Step 2: Evaluate options for filtering

   Only filtering the examples list before creating the template ensures empty outputs are excluded properly.

3. Final Answer:

   Filter the examples list before passing it to FewShotPromptTemplate constructor -> Option A

4. Quick Check:

   Pre-filter examples before constructor = A [OK]

Hint: Filter examples before creating the prompt template [OK]

Common Mistakes:

• Trying to filter inside example_prompt formatting
• Assuming Langchain auto-filters empty outputs
• Filtering after formatting instead of before