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⚡ Bolt: Replace df.iterrows() with zip() for faster batch evaluation#2

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bolt/pandas-iterrows-optimization-915598282802158971
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⚡ Bolt: Replace df.iterrows() with zip() for faster batch evaluation#2
dhanush342 wants to merge 1 commit intomainfrom
bolt/pandas-iterrows-optimization-915598282802158971

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💡 What: Replaced the slow df.iterrows() loop in web/streamlit_dashboard.py with fast iteration over parallel lists using zip().
🎯 Why: df.iterrows() is a known performance bottleneck in Pandas because it constructs a new Series object for every row. This slows down the batch evaluation process.
📊 Impact: Significantly reduces row iteration overhead, speeding up the data processing loop (often 10-100x faster than iterrows for large dataframes).
🔬 Measurement: Verify by running the Streamlit dashboard (streamlit run web/streamlit_dashboard.py) and processing a large batch CSV. The overhead between LLM inferences will be noticeably lower.


PR created automatically by Jules for task 915598282802158971 started by @dhanush342

Co-authored-by: dhanush342 <187305764+dhanush342@users.noreply.github.com>
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Copilot AI review requested due to automatic review settings March 17, 2026 22:21
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Pull request overview

This PR optimizes the Streamlit batch evaluation loop by removing pandas.DataFrame.iterrows() usage in run_batch, aiming to reduce per-row overhead during large batch runs in the dashboard.

Changes:

  • Replaced df.iterrows() with parallel-column iteration using zip() in run_batch.
  • Added a .jules/bolt.md note documenting df.iterrows() as a pandas performance anti-pattern and suggesting alternatives.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File Description
web/streamlit_dashboard.py Refactors batch loop iteration to avoid iterrows() overhead.
.jules/bolt.md Adds a repository note about avoiding df.iterrows() in performance-sensitive code.

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Comment on lines +46 to +47
problem_series = df[problem_col].astype(str).tolist()
reference_series = df[answer_col].tolist() if answer_col and answer_col in df.columns else [None] * total
reference = row[answer_col]
# ⚡ Bolt Optimization: Replacing slow df.iterrows() with fast iteration over parallel arrays/series
# This avoids the high overhead of creating a Series object for every row
# and safely handles dynamic column names and indices.
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2 participants