Pivot long to wide transformation dict

def pivot_long_to_wide(rows, key_col, value_col, id_cols=None):
    """
    Convert long-format data (list of dicts) to wide format.
    
    Args:
        rows: List of dicts in long format
        key_col: Column name to pivot on (becomes new column headers)
        value_col: Column name whose values become the cell values
        id_cols: List of columns to keep as identifiers (defaults to all except key/value cols)
    
    Returns:
        List of dicts in wide format
    """
    if id_cols is None:
        id_cols = [k for k in rows[0] if k not in (key_col, value_col)]
    
    # Group rows by identifier values
    grouped = {}
    for row in rows:
        key = tuple(row[c] for c in id_cols)
        if key not in grouped:
            grouped[key] = {}
        grouped[key][row[key_col]] = row[value_col]
    
    # Build wide-format rows
    result = []
    for key_values, pivot_map in grouped.items():
        wide_row = dict(zip(id_cols, key_values))
        wide_row.update(pivot_map)
        result.append(wide_row)
    
    return result


if __name__ == "__main__":
    data = [
        {"month": "Jan", "region": "North", "sales": 100},
        {"month": "Jan", "region": "South", "sales": 150},
        {"month": "Feb", "region": "North", "sales": 120},
        {"month": "Feb", "region": "South", "sales": 180},
    ]
    
    result = pivot_long_to_wide(data, key_col="month", value_col="sales", id_cols=["region"])
    for row in result:
        print(row)