# Misterious appearance of Plots MIME output in Jupyterlab

**URL:** <https://discourse.julialang.org/t/misterious-appearance-of-plots-mime-output-in-jupyterlab/44485>\
**Category:** General Usage\
**Tags:** plotting\
**Created:** [August 7, 2020, 9:48am UTC](https://discourse.julialang.org/t/misterious-appearance-of-plots-mime-output-in-jupyterlab/44485 "2020-08-07T09:48:23Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![alusiani](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/alusiani/32/16415_2.png) [@alusiani](https://discourse.julialang.org/u/alusiani)\
**Post date:** [August 7, 2020, 9:48am UTC](https://discourse.julialang.org/t/misterious-appearance-of-plots-mime-output-in-jupyterlab/44485/1 "2020-08-07T09:48:23Z")

</div>

I am puzzled by why a plot is shown in Jupyterlab despite I take all precautions for it not to be, when I call savefig().

In short, if I do

```julia
using Plots

plot(range, range.^2);
savefig("a.pdf");
nothing

```

in Jupyterlab, then the plot is shown, despite I put semicolons, and I set the output of the cell to be nothing.

If I do

```julia
plot(range, range.^2);

```

no plot is shown, as desired.

If I do

```julia
plot(range, range.^2);

```

and in a separate cell

```julia
savefig("a.pdf")

```

no plot is shown!

Furthermore, if I set “fmt = :svg” to get SVG plots by default, I do get SVG plots when using “plot()” but savefig() always produces PNG plots, and there is no way to silence this production in the Jupyterlab cell output.

There should be a weird interaction between Plots and Jupyterlab. I am triying to understand what happens but I try also to see if anybody more expert than me has any insight. I have collected my tests in this notebook: [https://gist.github.com/3ffefb4183fe026d5572baecdcde8808](https://gist.github.com/3ffefb4183fe026d5572baecdcde8808) .

---

<div class="post-metadata">

**Author:** ![alusiani](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/alusiani/32/16415_2.png) [@alusiani](https://discourse.julialang.org/u/alusiani)\
**Post date:** [August 8, 2020, 7:03am UTC](https://discourse.julialang.org/t/misterious-appearance-of-plots-mime-output-in-jupyterlab/44485/2 "2020-08-08T07:03:52Z")

</div>

The behaviour I observe is due to the fact that I am using PyPlot as backend, savefig() invokes the appropriate code in PyPlot to save a plot, preparing a “figure”, and PyPlot sets the following post-execution hook for any IJulia cell:

```julia
Main.IJulia.push_postexecute_hook(display_figs)

```

apparently, the preparation of a figure in PyPlot code for saving a plot sets up something that is treated by the hook as something to be shown in the Jupyter cell output.

In order to disable this behaviour, a savefigsilent() function can be defined as follows:

```julia
function savefigsilent(plt, fn::AbstractString)
  ##--- brutally close all pending figures prepared for display according to PyPlot
  for manager in PyPlot.Gcf."get_all_fig_managers"()
    f = manager."canvas"."figure"
    if f.number ∉ PyPlot.withfig_fignums
      ##--- close only figures not suspended for further handling
      close(f.number)
    end
  end
  savefig(plt, fn)
end
savefigsilent(fn::AbstractString) = savefigsilent(current(), fn::AbstractString)

```