Python Excel Mini Cookbook

To get you started, I’ve illustrated a number of common tasks you can do with Python and Excel. Each program below is a self contained example, just copy it, paste it and run it. A few things to note:

  • These examples were tested in Excel 2007, they should work fine in earlier versions as well after changing the extension of the file within the wb.SaveAs() statement from .xlsx to .xls
  • If you’re new to this, I recommend typing these examples by hand into IDLE, IPython or the Python interpreter, then watching the effect in Excel as you enter the commands. To make Excel visible add the line excel.Visible = True after the excel =win32.gencache.EnsureDispatch('Excel.Application') line in the script
  • These are simple examples with no error checking. Make sure the output files doesn’t exist before running the script. If the script crashes, it may leave a copy of Excel running in the background. Open the Windows Task Manager and kill the background Excel process to recover.
  • These examples contain no optimization. You typically wouldn’t use a for loop to iterate through data in individual cells, it’s provided here for illustration only.

Open Excel, Add a Workbook

The following script simply invokes Excel, adds a workbook and saves the empty workbook.

#
# Add a workbook and save (Excel 2007)
# For older versions of excel, use the .xls file extension
#
import win32com.client as win32
excel = win32.gencache.EnsureDispatch('Excel.Application')
wb = excel.Workbooks.Add()
wb.SaveAs('add_a_workbook.xlsx')
excel.Application.Quit()

Open an Existing Workbook

This script opens an existing workbook and displays it (note the statement excel.Visible =True). The file workbook1.xlsx must already exist in your “My Documents” directory. You can also open spreadsheet files by specifying the full path to the file as shown below. Using r'in the statement r'C:\myfiles\excel\workbook2.xlsx' automatically escapes the backslash characters and makes the file name a bit more concise.

#
# Open an existing workbook
#
import win32com.client as win32
excel = win32.gencache.EnsureDispatch('Excel.Application')
wb = excel.Workbooks.Open('workbook1.xlsx')
# Alternately, specify the full path to the workbook 
# wb = excel.Workbooks.Open(r'C:\myfiles\excel\workbook2.xlsx')
excel.Visible = True

Add a Worksheet

This script creates a new workbook with three sheets, adds a fourth worksheet and names it MyNewSheet.

#
# Add a workbook, add a worksheet,
# name it 'MyNewSheet' and save
#
import win32com.client as win32
excel = win32.gencache.EnsureDispatch('Excel.Application')
wb = excel.Workbooks.Add()
ws = wb.Worksheets.Add()
ws.Name = "MyNewSheet"
wb.SaveAs('add_a_worksheet.xlsx')
excel.Application.Quit()

Ranges and Offsets

This script illustrates different techniques for addressing cells by using the Cells() and Range()operators. Individual cells can be addressed using Cells(row,column), where row is the row number, column is the column number, both start from 1. Groups of cells can be addressed using Range(), where the argument in the parenthesis can be a single cell denoted by its textual name (eg "A2"), a group noted by a textual name with a colon (eg "A3:B4") or a group denoted with two Cells() identifiers (eg ws.Cells(1,1),ws.Cells(2,2)). The Offsetmethod provides a way to address a cell based on a reference to another cell.

#
# Using ranges and offsets
#
import win32com.client as win32
excel = win32.gencache.EnsureDispatch('Excel.Application')
wb = excel.Workbooks.Add()
ws = wb.Worksheets("Sheet1")
ws.Cells(1,1).Value = "Cell A1"
ws.Cells(1,1).Offset(2,4).Value = "Cell D2"
ws.Range("A2").Value = "Cell A2"
ws.Range("A3:B4").Value = "A3:B4"
ws.Range("A6:B7,A9:B10").Value = "A6:B7,A9:B10"
wb.SaveAs('ranges_and_offsets.xlsx')
excel.Application.Quit()

Autofill Cell Contents

This script uses Excel’s autofill capability to examine data in cells A1 and A2, then autofill the remaining column of cells through A10.

#
# Autofill cell contents
#
import win32com.client as win32
excel = win32.gencache.EnsureDispatch('Excel.Application')
wb = excel.Workbooks.Add()
ws = wb.Worksheets("Sheet1")
ws.Range("A1").Value = 1
ws.Range("A2").Value = 2
ws.Range("A1:A2").AutoFill(ws.Range("A1:A10"),win32.constants.xlFillDefault)
wb.SaveAs('autofill_cells.xlsx')
excel.Application.Quit()

Cell Color

This script illustrates adding an interior color to the cell using Interior.ColorIndex. Column A, rows 1 through 20 are filled with a number and assigned that ColorIndex.

#
# Add an interior color to cells
#
import win32com.client as win32
excel = win32.gencache.EnsureDispatch('Excel.Application')
wb = excel.Workbooks.Add()
ws = wb.Worksheets("Sheet1")
for i in range (1,21):
    ws.Cells(i,1).Value = i
    ws.Cells(i,1).Interior.ColorIndex = i
wb.SaveAs('cell_color.xlsx')
excel.Application.Quit()

Column Formatting

This script creates two columns of data, one narrow and one wide, then formats the column width with the ColumnWidth property. You can also use the Columns.AutoFit() function to autofit all columns in the spreadsheet.

#
# Set column widths
#
import win32com.client as win32
excel = win32.gencache.EnsureDispatch('Excel.Application')
wb = excel.Workbooks.Add()
ws = wb.Worksheets("Sheet1")
ws.Range("A1:A10").Value = "A"
ws.Range("B1:B10").Value = "This is a very long line of text"
ws.Columns(1).ColumnWidth = 1
ws.Range("B:B").ColumnWidth = 27
# Alternately, you can autofit all columns in the worksheet
# ws.Columns.AutoFit()
wb.SaveAs('column_widths.xlsx')
excel.Application.Quit()

Copying Data from Worksheet to Worksheet

This script uses the FillAcrossSheets() method to copy data from one location to all other worksheets in the workbook. Specifically, the data in the range A1:J10 is copied from Sheet1 to sheets Sheet2 and Sheet3.

#
# Copy data and formatting from a range of one worksheet
# to all other worksheets in a workbook
#
import win32com.client as win32
excel = win32.gencache.EnsureDispatch('Excel.Application')
wb = excel.Workbooks.Add()
ws = wb.Worksheets("Sheet1")
ws.Range("A1:J10").Formula = "=row()*column()"
wb.Worksheets.FillAcrossSheets(wb.Worksheets("Sheet1").Range("A1:J10"))
wb.SaveAs('copy_worksheet_to_worksheet.xlsx')
excel.Application.Quit()

Format Worksheet Cells

This script creates two columns of data, then formats the font type and font size used in the worksheet. Five different fonts and sizes are used, the numbers are formatted using a monetary format.

#
# Format cell font name and size, format numbers in monetary format
#
import win32com.client as win32
excel = win32.gencache.EnsureDispatch('Excel.Application')
wb = excel.Workbooks.Add()
ws = wb.Worksheets("Sheet1")

for i,font in enumerate(["Arial","Courier New","Garamond","Georgia","Verdana"]):
    ws.Range(ws.Cells(i+1,1),ws.Cells(i+1,2)).Value = [font,i+i]
    ws.Range(ws.Cells(i+1,1),ws.Cells(i+1,2)).Font.Name = font
    ws.Range(ws.Cells(i+1,1),ws.Cells(i+1,2)).Font.Size = 12+i

ws.Range("A1:A5").HorizontalAlignment = win32.constants.xlRight
ws.Range("B1:B5").NumberFormat = "$###,##0.00"
ws.Columns.AutoFit()
wb.SaveAs('format_cells.xlsx')
excel.Application.Quit()

Setting Row Height

This script illustrates row height. Similar to column height, row height can be set with the RowHeight method. You can also useAutoFit() to automatically adjust the row height based on cell contents.

#
# Set row heights and align text within the cell
#
import win32com.client as win32
excel = win32.gencache.EnsureDispatch('Excel.Application')
wb = excel.Workbooks.Add()
ws = wb.Worksheets("Sheet1")
ws.Range("A1:A2").Value = "1 line"
ws.Range("B1:B2").Value = "Two\nlines"
ws.Range("C1:C2").Value = "Three\nlines\nhere"
ws.Range("D1:D2").Value = "This\nis\nfour\nlines"
ws.Rows(1).RowHeight = 60
ws.Range("2:2").RowHeight = 120
ws.Rows(1).VerticalAlignment = win32.constants.xlCenter
ws.Range("2:2").VerticalAlignment = win32.constants.xlCenter

# Alternately, you can autofit all rows in the worksheet
# ws.Rows.AutoFit()

wb.SaveAs('row_height.xlsx')
excel.Application.Quit()

Prerequisites

Python (refer to http://www.python.org)

Win32 Python module (refer to http://sourceforge.net/projects/pywin32)

Microsoft Excel (refer to http://office.microsoft.com/excel)

Source Files and Scripts

Source for the program and data text file are available athttp://github.com/pythonexcels/examples

That’s all for now, thanks — Dan