Extract Error Patterns from Logs | Dataford Interview Questions

You are given log lines from an Apple service and a list of error patterns to track. Write a Python function that scans the logs and returns how many times each pattern appears, along with the matching log lines for each pattern.

A log line matches a pattern if the pattern appears as a case-sensitive substring anywhere in that line. A single line may match multiple patterns. Ignore empty log lines.

Formal Specification

Input:
- logs: a list of strings, where each string is one log line
- patterns: a list of unique strings representing error patterns to search for
Output:
- A dictionary where each key is a pattern and each value is another dictionary with:
  - count: number of matching log lines
  - lines: list of matching log lines in original order

Constraints

1 <= len(logs) <= 10^4
1 <= len(patterns) <= 100
0 <= len(logs[i]) <= 500
1 <= len(patterns[i]) <= 50
patterns contains unique strings
Matching is case-sensitive substring matching

Function Signature

def extract_error_patterns(logs, patterns):

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