M2_UGL_1 generated code gives error

Course Q&A Agentic AI
,
1

In this lab, at cell 9, there is a function:

Generate initial code

code_v1 = generate_chart_code(
instruction=“Create a plot comparing Q1 coffee sales in 2024 and 2025 using the data in coffee_sales.csv.”,
model=“gpt-4o-mini”,
out_path_v1=“chart_v1.png”
)

utils.print_html(code_v1, title=“LLM output with first draft code”)

And LLM gives generated code:

LLM output with first draft code

<execute_python>
import pandas as pd
import matplotlib.pyplot as plt

# Filter data for Q1 of 2024 and 2025
df['date'] = pd.to_datetime(df['date'] + ' ' + df['time'])
df_q1 = df[(df['quarter'] == 1) & (df['year'].isin([2024, 2025]))]

# Group by year and coffee name, then sum the prices
sales = df_q1.groupby(['year', 'coffee_name'])['price'].sum().unstack()

# Plotting
sales.plot(kind='bar', figsize=(10, 6))
plt.title('Q1 Coffee Sales Comparison (2024 vs 2025)')
plt.xlabel('Coffee Name')
plt.ylabel('Total Sales ($)')
plt.legend(title='Year')
plt.xticks(rotation=45)
plt.tight_layout()

# Save the figure
plt.savefig('chart_v1.png', dpi=300)
plt.close()
</execute_python>

If you run this piece of code, it gives run time error:
--> 273     res_values = op(left, right)
    274 else:
    275     # TODO we should handle EAs consistently and move this check before the if/else
    276     # (https://github.com/pandas-dev/pandas/issues/41165)
    277     # error: Argument 2 to "_bool_arith_check" has incompatible type
    278     # "Union[ExtensionArray, ndarray[Any, Any]]"; expected "ndarray[Any, Any]"
    279     _bool_arith_check(op, left, right)  # type: ignore[arg-type]

TypeError: unsupported operand type(s) for +: 'DatetimeArray' and 'str'

I checked and found the error is at this line:

df['date'] = pd.to_datetime(df['date'] + ' ' + df['time'])

The reason is that:  
Issue: TypeError from trying to add a pandas DatetimeArray and a string at the line df['date'] + ' ' + df['time'].
Root cause: load_and_prepare_data in utils.py already converts date to datetime64, so df['date'] is not a string and cannot be concatenated with df['time'].
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2

I got same error. Asked model to reflect, provided error dump. Mode came back with same code

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3

same issue here

4

I encountered the same error described above. Interestingly, when I copied the code to my local system (Python 3.13.9), it executed without issues. The root cause appears to be regional date format inconsistencies rather than a code bug. The prompt instructs the LLM to anticipate dates in (M/D/YY) format (U.S. style), but if the platform’s execution environment is outside the U.S., date conversion in utils.py follows the local format, which may differ from M/D/YY. This mismatch can cause parsing errors when pandas attempts to interpret ambiguous dates. To resolve this, change the date format in Cell 9 to match your local format, and the code will run without error.

5

I asked ChatGPT to reflect on this error and it produced a relatively complex solution involving implementation of error checking in the code. While the solution worked, the LLM was unable to identify the actual reason for the error.

6

I modified the prompt to include an instruction on cell 9:

- date (M/D/YY) (Make sure date is a string)
- time (HH:MM)  (Make sure time is a string)

And then everything works.
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