how can i build this (trying to contribute)

[andiejs]

I'd like to modify the code in the .opam lib folder and then rebuild and test to eventually contribute here.

in ~/.opam/4.13.1/lib/matplotlib running "opam ins ." on unchanged code downloaded from opam gives the error quoted below.

I'm not sure if I have totally the wrong approach to building this (I don't know how to use dune...), or if there's some other problem. Is there a simple way to build the package and install it?

Thanks!

monster@Clementine ~/.opam/4.13.1/lib/matplotlib $ opam ins .
matplotlib is now pinned to file:///home/monster/.opam/4.13.1/lib/matplotlib (version dev)
The following actions will be performed:
  ↗ upgrade matplotlib 0.2 to dev*

<><> Gathering sources ><><><><><><><><><><><><><><><><><><><><><><><><><><><><>
[matplotlib.dev] synchronised from file:///home/monster/.opam/4.13.1/lib/matplotlib

<><> Processing actions <><><><><><><><><><><><><><><><><><><><><><><><><><><><>
[ERROR] The compilation of matplotlib failed at
        "/home/monster/.opam/opam-init/hooks/sandbox.sh build dune build -p
        matplotlib -j 3 @install".

#=== ERROR while compiling matplotlib.dev =====================================#
# context     2.0.7 | linux/x86_64 | ocaml-base-compiler.4.13.1 | pinned(file:///home/monster/.opam/4.13.1/lib/matplotlib)
# path        ~/.opam/4.13.1/.opam-switch/build/matplotlib.dev
# command     ~/.opam/opam-init/hooks/sandbox.sh build dune build -p matplotlib -j 3 @install
# exit-code   1
# env-file    ~/.opam/log/matplotlib-51452-05296d.env
# output-file ~/.opam/log/matplotlib-51452-05296d.out
### output ###
# Error: I don't know about package matplotlib (passed through --only-packages)



<><> Error report <><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><>
┌─ The following actions failed
│ λ build matplotlib dev
└─ 
╶─ No changes have been performed