Excel Automation

# Create a formatted Excel report
uv run --with openpyxl scripts/create_formatted_excel.py output.xlsx

# Parse a complex xlsm that openpyxl can't handle
uv run scripts/parse_complex_excel.py model.xlsm              # List sheets
uv run scripts/parse_complex_excel.py model.xlsm "DCF"        # Extract a sheet
uv run scripts/parse_complex_excel.py model.xlsm --fix        # Fix corrupted names

# Control Excel via AppleScript (with timeout to prevent hangs)
timeout 5 osascript -e 'tell application "Microsoft Excel" to activate'

Is the file simple (data export, no VBA, <1MB)?
├─ YES → openpyxl or pandas
└─ NO
   ├─ Is it .xlsm or from investment bank / >1MB?
   │   └─ YES → zipfile + xml.etree.ElementTree (stdlib)
   └─ Is it truly .xls (BIFF format)?
       └─ YES → xlrd

from openpyxl.styles import Font, PatternFill, Border, Side, Alignment

# Fonts
BLUE_FONT = Font(color="0000FF", size=10, name="Calibri")
BLACK_FONT_BOLD = Font(color="000000", size=10, name="Calibri", bold=True)
GREEN_FONT = Font(color="008000", size=10, name="Calibri")
HEADER_FONT = Font(color="FFFFFF", size=12, name="Calibri", bold=True)

# Fills
DARK_BLUE_FILL = PatternFill("solid", fgColor="4472C4")
LIGHT_BLUE_FILL = PatternFill("solid", fgColor="D9E1F2")
INPUT_GREEN_FILL = PatternFill("solid", fgColor="E2EFDA")
LIGHT_GRAY_FILL = PatternFill("solid", fgColor="F2F2F2")

# Borders
THIN_BORDER = Border(bottom=Side(style="thin", color="B2B2B2"))
BOTTOM_DOUBLE = Border(bottom=Side(style="double", color="000000"))

from openpyxl.formatting.rule import ColorScaleRule

rule = ColorScaleRule(
    start_type="min", start_color="F8696B",   # Red (low)
    mid_type="percentile", mid_value=50, mid_color="FFEB84",  # Yellow (mid)
    end_type="max", end_color="63BE7B"         # Green (high)
)
ws.conditional_formatting.add(f"B2:F6", rule)

uv run --with openpyxl scripts/create_formatted_excel.py

file.xlsx (ZIP archive)
├── [Content_Types].xml
├── xl/
│   ├── workbook.xml          ← Sheet names + order
│   ├── sharedStrings.xml     ← All text values (lookup table)
│   ├── worksheets/
│   │   ├── sheet1.xml        ← Cell data for sheet 1
│   │   ├── sheet2.xml        ← Cell data for sheet 2
│   │   └── ...
│   └── _rels/
│       └── workbook.xml.rels ← Maps rId → sheetN.xml
└── _rels/.rels

import zipfile
import xml.etree.ElementTree as ET

MAIN_NS = 'http://schemas.openxmlformats.org/spreadsheetml/2006/main'
REL_NS = 'http://schemas.openxmlformats.org/officeDocument/2006/relationships'
RELS_NS = 'http://schemas.openxmlformats.org/package/2006/relationships'

def get_sheet_path(zf, sheet_name):
    """Resolve sheet name to physical XML file path inside ZIP."""
    # Step 1: workbook.xml → find rId for the sheet name
    wb_xml = ET.fromstring(zf.read('xl/workbook.xml'))
    sheets = wb_xml.findall(f'.//{{{MAIN_NS}}}sheet')
    rid = None
    for s in sheets:
        if s.get('name') == sheet_name:
            rid = s.get(f'{{{REL_NS}}}id')
            break
    if not rid:
        raise ValueError(f"Sheet '{sheet_name}' not found")

    # Step 2: workbook.xml.rels → map rId to file path
    rels_xml = ET.fromstring(zf.read('xl/_rels/workbook.xml.rels'))
    for rel in rels_xml.findall(f'{{{RELS_NS}}}Relationship'):
        if rel.get('Id') == rid:
            return 'xl/' + rel.get('Target')

    raise ValueError(f"No file mapping for {rid}")

def extract_cells(zf, sheet_path):
    """Extract all cell values from a sheet XML."""
    # Build shared strings lookup
    shared = []
    try:
        ss_xml = ET.fromstring(zf.read('xl/sharedStrings.xml'))
        for si in ss_xml.findall(f'{{{MAIN_NS}}}si'):
            texts = si.itertext()
            shared.append(''.join(texts))
    except KeyError:
        pass  # No shared strings

    # Parse sheet cells
    sheet_xml = ET.fromstring(zf.read(sheet_path))
    rows = sheet_xml.findall(f'.//{{{MAIN_NS}}}row')

    data = {}
    for row in rows:
        for cell in row.findall(f'{{{MAIN_NS}}}c'):
            ref = cell.get('r')         # e.g., "A1"
            cell_type = cell.get('t')   # "s" = shared string, None = number
            val_el = cell.find(f'{{{MAIN_NS}}}v')

            if val_el is not None and val_el.text:
                if cell_type == 's':
                    data[ref] = shared[int(val_el.text)]
                else:
                    try:
                        data[ref] = float(val_el.text)
                    except ValueError:
                        data[ref] = val_el.text
    return data