Jupyter notebook: Use pgf code instead of pdf/svg image for export to latex

karlroyen · January 14, 2020, 1:54pm

When displaying DataFrames in a Jupyter notebook they are nicely rendered using html. When you export the notebook to latex they are nicely exported as latex code creating that table.

Is it possible to have the same functionality for plots created with PGFPlots.jl or PGFPlotsX.jl? Meaning if I export a jupyter notebook to latex I would get a latex document that uses a the pgf code to display the plot instead of including an svg or pdf image of it.

I’m not sure in which package (IJulia, ipython, nbconvert, Plots.jl, PGFPlots(X).jl or a combination of those) this would have to be implemented.

Tamas_Papp · January 14, 2020, 2:18pm

PGFPlotsX should work fine in Jupyter notebooks, and you can save both pdf and svg images, or LaTeX source (pgfplots) directly. See the manual:

https://kristofferc.github.io/PGFPlotsX.jl/dev/man/save.html

karlroyen · January 14, 2020, 2:33pm

Yes, displaying the plots in a notebook works all fine. And converting the notebook to latex with for example jupyter-nbconvert --to latex mynotebook.ipynb works also fine.

However the plots are included as images (pdf or svg) in the generated latex document. I wonder if it would be possible for them to be automatically included as pgf plots/tikz code instead. Similar to how it already happens with tables.

kristoffer.carlsson · January 14, 2020, 2:42pm

It might be enough for PGFPlotsX to define a show method for the text/latex MIME type.

karlroyen · January 14, 2020, 3:14pm

A quick test of adding

Base.show(io::IO, ::MIME"text/latex", p::_SHOWABLE) = print_tex(io, p)

to tikzdocument.jl actually works for the export.

However in the notebook itself it is now also only displayed as the latex source . Is there some priority list that IJulia uses to decide which show method to use?

edit: that frowning smiley looks way to angry…

kristoffer.carlsson · January 14, 2020, 3:23pm

IJulia should make all of these MIME types be sent for the object:

github.com

JuliaLang/IJulia.jl/blob/bf0a53086545fe0f0695dc6e7c5ef35f047f4af5/src/display.jl#L6-L28


"""
A vector of MIME types (or vectors of MIME types) that IJulia will try to
render. IJulia will try to render every MIME type specified in the first level
of the vector. If a vector of MIME types is specified, IJulia will include only
the first MIME type that is renderable (this allows for the expression of
priority and exclusion of redundant data).


For example, since "text/plain" is specified as a first-child of the array,
IJulia will always try to include a "text/plain" representation of anything that
is displayed. Since markdown and html are specified within a sub-vector, IJulia
will always try to render "text/markdown", and will only try to render
"text/html" if markdown isn't possible.
"""
const ijulia_mime_types = Vector{Union{MIME, AbstractVector{MIME}}}([
    MIME("text/plain"),
    MIME("image/svg+xml"),
    [MIME("image/png"),MIME("image/jpeg")],
    [
        MIME("text/markdown"),
        MIME("text/html"),

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What determines what actually gets rendered and shown on screen, I am not sure.

karlroyen · January 14, 2020, 4:02pm

After some research it seems like the priority list is hard coded and Latex takes precedence above images (source).

Which would be fine if the mathjax engine used to display latex would be able to handle pgfplots.

Tamas_Papp · January 15, 2020, 8:31am

I am not quite sure you would want this, even if it was implemented.

While rendering math is now really fast with MathJaX (and even better with KaTeX), pgfplots is comparatively expensive, even with engines like LuaTeX, and uses a lot of TeX functionality and special backengs (via TikZ/pgf). One would essentially have to implement a rather complete TeX engine in the browser.

karlroyen · January 17, 2020, 8:16am

Yes, you are probably right.

I’ll try to use a custom MIME type like "text/pgf" for the pgf source instead and use a custom template for nbconvert.

Tamas_Papp · January 17, 2020, 8:49am

Let us know how it goes, and maybe submit a PR if it works. Output as MIME"text/pgf" should be simple to implement with a simple wrapper.

karlroyen · January 18, 2020, 10:54am

I have gotten a first working version using the custom mime type “text/pgf” and a custom latex exporter.

I hadn’t had to change much on the Julia side except from adding the according show methods and registering the new mime type with IJulia.

But I had to add a custom exporter for nbconvert that prefers “text/pgf” over image mimes and adds the according pgf source to the files.

You can give it a try at https://github.com/karlwessel/LatexWithPGFPlots

Big parts missing are support for Plots.jl and a bit clean up of the generated files for the latex document.