(xyplots)=
# x-y plots

:::::{admonition} This page is a stub
:class: warning

Remember my joke that it takes a lifetime to learn ROOT?

Prior to 2024, I only discussed making x-y plots in an {ref}`advanced
exercise <root-folders>`. This was because, when I composed that section
of the course 15 years ago, the documentation for
[TGraph](https://root.cern.ch/doc/master/classTGraph.html) and
[TGraphErrors](https://root.cern.ch/doc/master/classTGraphErrors.html)
was poor.

While preparing an x-y plot for the 2024 presentation (it's on the
last slide of [this PDF
file](https://www.nevis.columbia.edu/~seligman/root-class/ClassOverview2024.pdf)
if you're interested), I discovered that someone on the ROOT team had
worked hard. `TGraph` and `TGraphErrors` are now no more difficult to
use than Python's
[matplotlib](https://matplotlib.org/stable/users/index).

I only discovered this two days before I had to teach the tutorial!

For the 2025 class, I'll revise this page with some examples, along
with comparisons to matplotlib so you can decide which you'd prefer
to use.

Until then, if you're interested in making x-y plots in ROOT:

- See the {file}`graphs` sub-directory of the {ref}`ROOT examples
  <references>`. I suggest you start with
  [graph.C](https://root.cern/doc/master/graph_8C.html) and
  [gerrors.C](https://root.cern/doc/master/gmultierrors_8C.html).

- Consult the [TGraphPainter](https://root.cern.ch/doc/master/classTGraphPainter.html)
  web page for examples. You may also want to visit the 
  [TAttMarker](https://root.cern.ch/doc/master/classTAttMarker.html),
  [TAttLine](https://root.cern.ch/doc/master/classTAttLine.html), and
  [TGAxis](https://root.cern.ch/doc/master/classTGAxis.html) for documentation
  on the different plotting options. 

- In command-line ROOT, you can use the same tools you learned about
  in {ref}`plotting-function` and {ref}`saving-c1` to interactively
  edit your plot's appearance, save it as a .C macro, then examine the
  macro to learn the ROOT commands to get a plot to look the way you
  want.

- In a ROOT {ref}`notebook <notebook>`, you can use the {ref}`%jsroot
  magic command <magic-command>` to make an x-y plot interactive, so
  you're able to modify the plot in much the same way as in
  command-line ROOT. The difference is that you can't save the plot as
  a .C macro... at least, not yet!

:::{figure-md} xyplot-fig
:align: center

<img src="pict1_graph.C.png" alt="x-y plot from graph.C" width="75%">

The x-y plot from {file}`graph.C`. 
:::

There'll be more next year!

:::::