Plots.jl: Unkown key: axis

[crbinz]

I'm trying to remember how to use multiple axes. I found this example in the doc:

plot(Vector[randn(100),randn(100) * 100],axis=[:l :r],ylabel="LEFT",yrightlabel="RIGHT")

but that results in

LoadError: Unknown key: axis
while loading In[54], in expression starting on line 1

 in default at C:\Users\cbinz\.julia\v0.4\Plots\src\args.jl:468
 in warnOnUnsupported_args at C:\Users\cbinz\.julia\v0.4\Plots\src\args.jl:760
 in _apply_series_recipe at C:\Users\cbinz\.julia\v0.4\Plots\src\plot.jl:218
 in _plot! at C:\Users\cbinz\.julia\v0.4\Plots\src\plot.jl:538

It does in fact work with the UnicodePlots backend, but not with PyPlot or GR. I have not tried others.

[tbreloff]

Sorry to say, but that functionality has been temporarily removed. There is no axis = :right anymore. I want to generalize so you can put axes anywhere and overlay as many as you want. I'm open to api suggestions of what that should look like.

[crbinz]

That's too bad. The simple right/left was sufficient to cover all of my use cases, and I don't really have any suggestions for how a more general version should look.

[tbreloff]

I agree... I wish it was more straightforward to keep, but this is one feature that requires a lot of effort in each backend the way I was doing it, and it can be replaced pretty generically. I just have to do it.

[tbreloff]

Now that axis is a reserved keyword for defining attributes for each axis, we need an alternative method of specifying the "twin axes" or "right and left axes" that we previously had.

Really what I want is a simple way to make one subplot an inset with the other plot as its parent, and also allow for putting the tick labels on the right/left/top/bottom of any subplot. Then we can just draw 2 subplots over each other and get the same functionality. API bikeshedding please.

[tbreloff]

related: #337

[maximsch2]

Just to confirm - there is no way to do yaxis=:right right now? (maybe it is possible to work around it with recipes somehow?)
Is it possible to embed a pyplot figure as a part of multi-part Plots.jl figure?

[tbreloff]

What's really missing is a nice way to put the ticks on the opposite side. I'll take a look and see if there's a quick answer for that. Then it's just a Plots trick to overlay 2 subplots and link the x axis.

My request is still open though... what should the API look like? How would you like to tell plots that you want a "twin axis"?

[tbreloff]

I'll push it up soon, and I'll post an example of how to hack twin axes with it.

[tbreloff]

using Plots
gr()
plot(rand(10,2), right_margin=30px)
scatter!(rand(10), ymirror=true, xlink=1, inset=(1,bbox(0,0,1,1)), bg_inside=RGBA(0,0,0,0), subplot=2)

[tbreloff]

So there were a few steps to this hack:

• leave some room for the right axis labels
• create an inset plot, parent is the 1st subplot, bounding box starts at the origin and takes up 100%
• scatter call applies to 2nd subplot
• mirror the y axis
• link the x axes
• make the inset background invisible

[maximsch2]

Great, thanks! I'll try it tomorrow.

Re API: mirror seems fine. What was the issue with specifying yaxis=:left/:right? It seems like it can be generalized to xaxis=:top/:bottom as well.

[tbreloff]

I put the hack into a method twinx. It works similar to the same method in matplotlib. It takes one param: the parent subplot, and adds a new subplot with the same result as the hack above, returning the new Subplot object. (if you didn't know you can plot directly to a Subplot: plot!(sp, rand(10))) There's also the backup:

twinx(plt::Plot = current()) = twinx(plt[1])

Here's a full example (works on PyPlot and GR if you check out dev):

using Plots; gr()
plot(rand(10))
scatter!(twinx(), 5:14, randn(10))

When we eventually have legends and colorbars that can be shared across subplots then this should be a complete solution.

[maximsch2]

Twinx works almost perfectly! A small nitpick:

There is a weird interplay between twinx, ylabel and xticks:

Note that there is no ylabel on the right axis. To get it back I can:

• change xt = (at, map(string, at)) into xt = (a, map(string, a)) (e.g. do a continuous axis instead of the skipping one over)
• remove xticks altogether
• plot ticks from until 2016 instead of 2015
• also jumping over 3 years instead of 2 seems to help

As a sidenote, I'm messing with xticks because Plots.jl is deciding to interpolate x values even when they are integers (which makes them look weird as they are just years, 2007.5 is not a year). Is this an expected behaviour?

[tbreloff]

None of this is expected... first.. can you add extra margin and see if the guide shows up?

[maximsch2]

Yes, I can confirm that adding right_margin to the first plot call makes the label appear again!

[tbreloff]

ok so i just need to improve the margin calc. It's clear this is a hack :)

[maximsch2]

Any thoughts about the sidenote in my previous comment? Do you think adding a recipe that would force arrays of integers not to interpolate would make sense?

[tbreloff]

Thats beyond a recipe. Opening an issue is the best next step

[GravityAssisted]

Does this still work ?
I tried the following on pyplot, gr and pgfplots and got an error:

Plots.scatter(dvs,AllowableRends,m=(0.5),yticks=AllowableRends, xlab="Delta-V Per Rendezvous (arrival + departure, km/s)", ylab="Number of Rendezvous")
Plots.scatter!(twinx(),dvs,Imass,yticks=Imass,ylab="Initial S/C mass (kg)")

ERROR: LoadError: MethodError: no method matching getindex(::Plots.Series, ::Int64)
I used following definition for twinx

twinx(plt = Plots.current()) = twinx(plt[1])

[fbruetting]

Sorry to say, but that functionality has been temporarily removed. There is no axis = :right anymore. I want to generalize so you can put axes anywhere and overlay as many as you want. I'm open to api suggestions of what that should look like.

Is there a method for creating more than two y axes? When I try to use twinx() twice, I get overlapping ticks on the second y axis. Would be neat if something like this would be possible: Link (last image of the page)