Setting styles in Openpyxl

Question

I need advice on setting styles in Openpyxl.

I see that the NumberFormat of a cell can be set, but I also require setting of font colors and attributes (bold etc). T

Answer 1

Like openpyxl doc said:

This is an open source project, maintained by volunteers in their spare time. This may well mean that particular features or functions that you would like are missing.

I checked openpyxl source code, found that:

Till openpyxl 1.8.x, styles are mutable. Their attribute can be assigned directly like this:

from openpyxl.workbook import Workbook
from openpyxl.style import Color

wb = Workbook()
ws = wb.active
ws['A1'].style.font.color.index = Color.RED

However from of openpyxl 1.9, styles are immutable.

Styles are shared between objects and once they have been assigned they cannot be changed. This stops unwanted side-effects such as changing the style for lots of cells when instead of only one.

To create a new style object, you can assign it directly, or copy one from an existing cell's style with new attributes, answer to the question as an example(forgive my Chinese English):

from openpyxl.styles import colors
from openpyxl.styles import Font, Color
from openpyxl import Workbook
wb = Workbook()
ws = wb.active

a1 = ws['A1']
d4 = ws['D4']

# create a new style with required attributes
ft_red = Font(color=colors.RED) 
a1.font = ft_red

# you can also do it with function copy
ft_red_bold = ft_red.copy(bold=True)

# you can copy from a cell's style with required attributes
ft_red_sigle_underline = a1.font.copy(underline="single")

d4.font = ft_red_bold

# apply style to column E
col_e = ws.column_dimensions['E']
col_e.font = ft_red_sigle_underline

A cell' style contains these attributes: font, fill, border, alignment, protection and number_format. Check openpyxl.styles.

They are similar and should be created as an object, except number_format, its value is string type.

Some pre-defined number formats are available, number formats can also be defined in string type. Check openpyxl.styles.numbers.

from openpyxl.styles import numbers

# use pre-defined values
ws.cell['T49'].number_format = numbers.FORMAT_GENERAL
ws.cell(row=2, column=4).number_format = numbers.FORMAT_DATE_XLSX15

# use strings
ws.cell['T57'].number_format = 'General'
ws.cell(row=3, column=5).number_format = 'd-mmm-yy'
ws.cell['E5'].number_format = '0.00'
ws.cell['E50'].number_format = '0.00%'
ws.cell['E100'].number_format = '_ * #,##0_ ;_ * -#,##0_ ;_ * "-"??_ ;_ @_ '

Answer 2

As of openpyxl 2.0, setting cell styles is done by creating new style objects and by assigning them to properties of a cell.

There are several style objects: Font, PatternFill, Border, and Alignment. See the doc.

To change a style property of a cell, first you either have to copy the existing style object from the cell and change the value of the property or you have to create a new style object with the desired settings. Then, assign the new style object to the cell.

Example of setting the font to bold and italic of cell A1:

from openpyxl import Workbook
from openpyxl.styles import Font
# Create workbook
wb = Workbook()
# Select active sheet
ws = wb.active()
# Select cell A1
cell = ws['A1']
# Make the text of the cell bold and italic
cell.font = cell.font.copy(bold=True, italic=True)

Answer 3

For openpyxl version 2.4.1 and above use below code to set font color:

from openpyxl.styles import Font
from openpyxl.styles.colors import Color

ws1['A1'].font = Font(color = "FF0000")

hex codes for various colors can be found at: http://dmcritchie.mvps.org/excel/colors.htm

Answer 4

As of openpyxl-1.7.0 you can do this too:

cell.style.fill.start_color.index = "FF124191"

I've got a couple of helper functions which set a style on a given cell - things like headers, footers etc.

Answer 5

As of openpyxl version 1.5.7, I have successfully applied the following worksheet style options...

from openpyxl.reader.excel import load_workbook
from openpyxl.workbook import Workbook
from openpyxl.styles import Color, Fill
from openpyxl.cell import Cell

# Load the workbook...
book = load_workbook('foo.xlsx')

# define ws here, in this case I pick the first worksheet in the workbook...
#    NOTE: openpyxl has other ways to select a specific worksheet (i.e. by name
#    via book.get_sheet_by_name('someWorksheetName'))
ws = book.worksheets[0]

## ws is a openpypxl worksheet object
_cell = ws.cell('C1')

# Font properties
_cell.style.font.color.index = Color.GREEN
_cell.style.font.name = 'Arial'
_cell.style.font.size = 8
_cell.style.font.bold = True
_cell.style.alignment.wrap_text = True

# Cell background color
_cell.style.fill.fill_type = Fill.FILL_SOLID
_cell.style.fill.start_color.index = Color.DARKRED

# You should only modify column dimensions after you have written a cell in 
#     the column. Perfect world: write column dimensions once per column
# 
ws.column_dimensions["C"].width = 60.0

FYI, you can find the names of the colors in openpyxl/style.py... I sometimes I patch in extra colors from the X11 color names

class Color(HashableObject):
    """Named colors for use in styles."""
    BLACK = 'FF000000'
    WHITE = 'FFFFFFFF'
    RED = 'FFFF0000'
    DARKRED = 'FF800000'
    BLUE = 'FF0000FF'
    DARKBLUE = 'FF000080'
    GREEN = 'FF00FF00'
    DARKGREEN = 'FF008000'
    YELLOW = 'FFFFFF00'
    DARKYELLOW = 'FF808000'

Answer 6

As of openpyxl 2.0, styles are immutable.

If you have a cell, you can (e.g.) set bold text by:

cell.style = cell.style.copy(font=cell.style.font.copy(bold=True))

Yes, this is annoying.