Determining xlims

General Usage
1

Hi,

I really like the ability of Makie to set the x and y limits automatically but sometimes I want to use the limits to fine tune my plot. Is there a way of returning the x and y limits for an axis when they have been automatically set?

Thanks
Steve

1 Like
2

Hey Steve,

i’m not sure if there is a nicer option already but you can get them from the Axis internals:

using GLMakie
fig, ax, p = plot(rand(Point2, 4))

rectangle = ax.finallimits[]
xlimits = (rectangle.origin[1], rectangle.origin[1] + rectangle.widths[1])
ylimits = (rectangle.origin[2], rectangle.origin[2] + rectangle.widths[2])

Alternatively define a function to get them as Observables for the true interactive Makie experience

xlims(ax::Axis) = @lift ($(ax.finallimits).origin[1], $(ax.finallimits).origin[1] + $(ax.finallimits).widths[1])
ylims(ax::Axis) = @lift ($(ax.finallimits).origin[2], $(ax.finallimits).origin[2] + $(ax.finallimits).widths[2])
3

Shoutout to Plots.jl for

using Plots
plot(sin)
xlims()
# (-5.3, 5.3)
ylims()
# (-1.0596986628031682, 1.059331996217173)
1 Like
4 
xlims(ax::Axis) = @lift ($(ax.finallimits).origin[1], $(ax.finallimits).origin[1] + $(ax.finallimits).widths[1])
ylims(ax::Axis) = @lift ($(ax.finallimits).origin[2], $(ax.finallimits).origin[2] + $(ax.finallimits).widths[2])

xlims() = xlims(current_axis())
ylims() = ylims(current_axis())

:stuck_out_tongue: (plot(sin) still not possible in Makie though)

5

Is this equivalent:

xlims(ax::Axis=current_axis()) =
    @lift ($(ax.finallimits).origin[1], $(ax.finallimits).origin[1] + $(ax.finallimits).widths[1])
ylims(ax::Axis=current_axis()) =
    @lift ($(ax.finallimits).origin[2], $(ax.finallimits).origin[2] + $(ax.finallimits).widths[2])
1 Like
6

Thanks hexader, that’s a great help.

Just to make sure I have this correct…

this line xlims(ax::Axis) = @lift ($(ax.finallimits).origin[1], $(ax.finallimits).origin[1] + $(ax.finallimits).widths[1])
creates an observable for the finallimits
this observable it is initialised using xlims() = xlims(current_axis())

so, I should then create another observable that listens for changes to xlims()?

Does this look something like

makeadjustment = lift(xlims()) do
      my code to alter the plot
end

Thanks
Steve

7

Nearly. lift would create a new Observable makeadjustment which follows the changes of xlims(). If you want to call a specific function on change use on:

using GLMakie
fig, ax, p = plot(rand(Point2, 4))

xlims(ax::Axis=current_axis()) = @lift ($(ax.finallimits).origin[1], $(ax.finallimits).origin[1] + $(ax.finallimits).widths[1])
ylims(ax::Axis=current_axis()) = @lift ($(ax.finallimits).origin[2], $(ax.finallimits).origin[2] + $(ax.finallimits).widths[2])

on(xlims()) do l
    println("xlmits changed to $l")
end

xlims!(-2, 2) # prints "xlimits changed to (-2, 2)"

This function will be only called on change though and not on definition. So maybe you want to call autolimits!(ax) again after the on block to trigger the reaction.

8

Thanks hexaeder, that’s crystal clear now.