py-02-csv-groupby

1.000

8/8 tests· data

Proposed solution

```python
def group_sum(csv_text: str, key_col: str, val_col: str) -> dict[str, float]:
    lines = [line for line in csv_text.split('\n') if line.strip()]
    if not lines:
        return {}
    
    header = lines[0].split(',')
    key_index = header.index(key_col)
    val_index = header.index(val_col)
    
    result = {}
    for line in lines[1:]:
        parts = line.split(',')
        key = parts[key_index]
        try:
            value = float(parts[val_index])
            result[key] = result.get(key, 0) + value
        except ValueError:
            pass  # Ignore rows where val_col is not numeric
    
    return result
```

Test output (stdout)

........                                                                 [100%]
8 passed in 0.01s

System prompt

You are an expert programmer. Solve the task exactly as specified. Output your solution as fenced code blocks using the required file name(s) and the exact function/type signatures requested. Prefer correctness; do not include prose outside code unless asked.