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vega / vl-convert

Utilities for converting Vega-Lite specs from the command line and Python
BSD 3-Clause "New" or "Revised" License
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Graphing using data in a separate file from a local path (rust executable) #189

Open yuki-tsubaki opened 1 month ago

yuki-tsubaki commented 1 month ago

Context

v5 schema vl-convert 1.6.1 On GNU/Linux

Issue/Question

I am trying to plot something with vl-connect When I embed the data directly in the spec everything works properly and I get a nice svg showing the plot.

However since I often show multiple visualizations that use the same data (and just to make things cleaner) I would prefer to keep the data in a different file and reference it with the url.

I.e. {"data":{"url":"path/to/data.json"}...}

However, when I do this I never can get it to actually access the data and I end up with an empty scatter plot.

I've tried various permutations with the data in different places, full paths, relative paths to different directories, and more but I still haven't been able to get anything to work.

Can someone help and point out what I am missing here? Thanks in advance.

jonmmease commented 1 month ago

Hi @yuki-tsubaki, thanks for the idea. I'll need to play with it some, but have you tried using file:// urls? I think Vega defaults to treating paths without a protocol as being http.

We may be able to do something by customizing the Vega loader here:

https://github.com/vega/vl-convert/blob/9e72c4e7f88d50dc83a9da6b652af8f614b0433e/vl-convert-rs/src/converter.rs#L352-L368

And there's some info the Vega loader at https://github.com/vega/vega/tree/main/packages/vega-loader.

yuki-tsubaki commented 1 month ago

Thanks for such a fast reply. I have tried multiple different notations for the path to the data file.

I have tried with and without the file:// protocol for absolute (from root--e.g. /home/...data/hp-mpg-plot-data.json), relative (to the working directory--e.g. data/hp-mpg-plot-data.json), and relative (to the spec file--e.g. ../data/hp-mpg-plot-data.json) paths.

As a side note, (I have no clue on how actually practical this would be for the architecture this is using), having error messages would be nice. I see that the underlying JS does log failed loading when I put in a fake, non-data, or unavailable url, so if there were a way to send these to the standard output (when using a --debug flag for instance) would be helpful in figuring this stuff out.

mgilbir commented 1 month ago

@jonmmease I've been toying with something like that in this PR, but I didn't have time to finish it.