[Solved] What is wrong with this custom metric class that causes an error? class LengthDiff(Evaluation):... What is wrong with this custom metric class that causes an error? | LangChain

LangChain - Evaluation and Testing

What is wrong with this custom metric class that causes an error?

class LengthDiff(Evaluation):
    def evaluate(self, predictions, references):
        return abs(len(predictions) - len(references)) / len(references)

AIt returns a number instead of a score between 0 and 1

BIt does not implement the evaluate method

CIt uses abs() incorrectly causing a syntax error

DIt does not handle empty lists causing runtime error

Step-by-Step Solution

Solution:

Step 1: Analyze the evaluate method with empty references
If references=[], len(references)=0 causes ZeroDivisionError in the division.
Step 2: Identify the runtime error cause
The code divides by len(references) without checking if references is empty, causing runtime error.
Final Answer:
It does not handle empty lists causing runtime error -> Option D
Quick Check:
len(references)==0 -> ZeroDivisionError [OK]

Quick Trick: Check how method handles empty input lists [OK]

Common Mistakes:

MISTAKES

Assuming abs() causes syntax error
Thinking evaluate method is missing
Ignoring empty list edge cases

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What is wrong with this custom metric class that causes an error?

Step 1: Analyze the evaluate method with empty references

Step 2: Identify the runtime error cause

Final Answer:

Quick Check:

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