Altair ¶

To plot a altair figure in Excel you first create the figure in exactly the same way you would in any Python script using altair, and then use PyXLL’s plot function to show it in the Excel workbook.

Altair supports interactive charts and these are displayed in Excel using an interactive web control, where available [1].

The code below shows an Excel worksheet function that generates an altair figure and displays it in Excel.

# This example requies vega_datasets.
# Install using 'pip install vega_datasets'
from vega_datasets import data
from pyxll import xl_func, plot
import altair as alt

@xl_func
def altair_plot():
    # Get the sample data set
    source = data.cars()

    # Create the chart
    chart = alt.Chart(source).mark_circle(size=60).encode(
        x='Horsepower',
        y='Miles_per_Gallon',
        color='Origin'
    )

    # Show it in Excel using pyxll.plot
    plot(chart)

When this function is run in Excel the plot is shown just below the calling cell.

If the interactive web control is not available, the figure will instead be exported as a static image. This is done using altair_saver which also requires Selenium. Both of these must be installed before Altair can be used with PyXLL unless using the web control [1].

• altair_saver can be installed using pip install altair_saver or conda install -c conda-forge altair_saver.

• The easiest way to install Selenium is to use Anaconda and install it using either of the following commands:

  conda install selenium geckodriver firefox -c conda-forge
  

  or

  conda install selenium python-chromedriver-binary -c conda-forge
  

  If you are not using Anaconda you can use pip install selenium but you will also need to install a suitable web browser backend. See https://pypi.org/project/selenium/ for additional details about how to install Selenium.

If you have any problems with exporting plots as html or using the interactive web control, you can tell PyXLL to use a static image format instead by passing allow_html=False to plot.

When exporting as an image and not html, an SVG image may be used. If you version of Excel does not support SVG images (Excel 2016 or earlier) or you are having problems with the SVG image not displaying correctly you can tell PyXLL to use the PNG format instead by passing allow_svg=False to plot.

Footnotes