Broken Example Gallery

[domsl]

Hey, I love the example gallery of the docs a lot, because I always get confused which objects goes where after reading API, so the examples really help me grasp altair.
(Something like this aready confuses me alot :)

So I found several broken examples:

https://altair-viz.github.io/gallery/simple_histogram.html
https://altair-viz.github.io/gallery/cumulative_count_chart.html
https://altair-viz.github.io/gallery/binned_scatterplot.html
https://altair-viz.github.io/gallery/stripplot.html
https://altair-viz.github.io/gallery/histogram_with_a_global_mean_overlay.html
https://altair-viz.github.io/gallery/interactive_cross_highlight.html
https://altair-viz.github.io/gallery/multiple_interactions.html

(I stopped searching after the interactive ones.)

I tried searching for an issue that already reports that, but I did not find anything.

I do not know how to fix it unfortunately.

[jakevdp]

Sorry about that - this has been an issue for a couple months due to vega-datasets changing all their URLs, and I haven't had a chance to fix it.

[rlguarino]

I think some of the broken dashboards are because the Vegas datasets switched from underscore separated column names to space separated in vega/vega@8b16c45

I was able to fix some of the examples by updating the column names in the Vega editor: Open the Chart in the Vega Editor

I was going to send a find and replace CL for the chats that depend on the movie but I'm not sure if it will be right.
I started with IMDB Rating but reached the depth of my knowledge.
For example, how would I update the following code to have spaces instead of underscores?

https://github.com/altair-viz/altair/blob/4f6dd28b3d8d540533d59ad1b638f4da8480b87e/altair/examples/multiple_interactions.py#L26-L38

Is it valid to replace all of the dot accesses datum.IMDB_Rating with datum['IMDB Rating'] ?

[mattijn]

Yes. As is documented here https://vega.github.io/vega/docs/expressions/#datum

[mattlangeman]

I ran into similar issues while going through the uwdata visualization curriculum. As @rlguarino mentions, the movie dataset changed column names from underscore separated to space separated. This also required changing a bunch of datum.column_names to datum['column names'] and doing things with double quotes as below

alt.Chart(movies).mark_area().transform_calculate(
    NonUS_Gross="datum['Worldwide Gross'] - datum['US Gross']"
).encode(
    alt.X('month(Release Date):T'),
    alt.Y('median(NonUS_Gross):Q')
)

You can see an example of these changes in altair_data_transformation.ipynb

Note: I haven't figured out how to get my output cells to have embedded pngs, but the output looks good when I run it locally.

I am a bit new to the altair and vega communities, but would be happy to help with this if I can be useful.

[joelostblom]

@jakevdp @rlguarino I believe a fix to the docs has already been suggested in this PR #2241

[joelostblom]

This was fixed in the 4.2 release and the examples linked above are now working.