How to align lilaq plots inside subpar figure?

Questions
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1

Hi,
I’m trying to align these 3 lilaq plots. every plot gets set to the same width and the alignment in subpar is set to top + right. Maybe someone here has an idea what I’m missing :)

image
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Example code 
#{
  import "@preview/subpar:0.2.2"
  import "@preview/lilaq:0.4.0" as lq
  import "@preview/fancy-units:0.1.1": *

  let plot_width = 10cm
  let subplot_height = 4cm

  let T = 2.0 // total duration

  let s(t) = 3 * calc.pow(t / T, 2) - 2 * calc.pow(t / T, 3)
  let s_dot(t) = (6 * (t / T) - 6 * calc.pow(t / T, 2)) / T
  let s_ddot(t) = (6 - 12 * (t / T)) / calc.pow(T, 2)

  // Vector helpers (element-wise ops for 3D tuples)
  let vec_add(a, b) = (a.at(0) + b.at(0), a.at(1) + b.at(1), a.at(2) + b.at(2))
  let vec_sub(a, b) = (a.at(0) - b.at(0), a.at(1) - b.at(1), a.at(2) - b.at(2))
  let vec_scale(s, v) = (s * v.at(0), s * v.at(1), s * v.at(2))

  let q0 = (calc.pi, calc.pi / 2, 0)
  let qf = (calc.pi / 2, -calc.pi / 4, calc.pi / 3)

  let dq = vec_sub(qf, q0)

  let q(t) = vec_add(q0, vec_scale(s(t), dq))
  let q_dot(t) = vec_scale(s_dot(t), dq)
  let q_ddot(t) = vec_scale(s_ddot(t), dq)

  let n = 200
  let ts = lq.linspace(0, T, num: n)

  show lq.selector(lq.legend): set grid(columns: 6)

  // -- figure --
  subpar.grid(
    figure(
      lq.diagram(
        // title: [Cubic time-scaling along a joint-space path],
        xaxis: (
          label: [Time $t$ / #unit[s]],
        ),
        yaxis: (
          label: [Positions $q$ / #unit[rad]],
          locate-ticks: lq.locate-ticks-linear.with(unit: calc.pi),
          format-ticks: lq.format-ticks-linear.with(suffix: math.pi),
        ),
        width: plot_width,
        height: subplot_height,
        legend: (position: center + bottom, dy: -100%),

        lq.plot(ts, ts.map(t => q(t)).map(q => q.at(0)), mark: none, label: [Axis $1$]),
        lq.plot(ts, ts.map(t => q(t)).map(q => q.at(1)), mark: none, label: [Axis $2$]),
        lq.plot(ts, ts.map(t => q(t)).map(q => q.at(2)), mark: none, label: [Axis $3$]),
      ),
    ), <fig:trajectory-example-cubic-q>,
    figure(
      lq.diagram(
        xaxis: (
          label: [Time $t$ / #unit[s]],
        ),
        yaxis: (
          label: [Velocities $dot(q)$ / #unit[rad/s]],
        ),
        width: plot_width,
        height: subplot_height,
        legend: none,

        lq.plot(ts, ts.map(t => q_dot(t)).map(qd => qd.at(0)), mark: none, label: [$dot(q)_1$]),
        lq.plot(ts, ts.map(t => q_dot(t)).map(qd => qd.at(1)), mark: none, label: [$dot(q)_2$]),
        lq.plot(ts, ts.map(t => q_dot(t)).map(qd => qd.at(2)), mark: none, label: [$dot(q)_3$]),
      ),
    ), <fig:trajectory-example-cubic-qdot>,
    figure(
      lq.diagram(
        xaxis: (
          label: [Time $t$ / #unit[s]],
        ),
        yaxis: (
          label: [Accelerations $dot.double(q)$ / #unit[rad/s^2]],
        ),
        width: plot_width,
        height: subplot_height,
        legend: none,

        lq.plot(ts, ts.map(t => q_ddot(t)).map(qdd => qdd.at(0)), mark: none, label: [$dot.double(q)_1$]),
        lq.plot(ts, ts.map(t => q_ddot(t)).map(qdd => qdd.at(1)), mark: none, label: [$dot.double(q)_2$]),
        lq.plot(ts, ts.map(t => q_ddot(t)).map(qdd => qdd.at(2)), mark: none, label: [$dot.double(q)_3$]),
      ),
    ), <fig:trajectory-example-cubic-qddot>,

    columns: 1fr,
    align: top + right,
    caption: [Example trajectory: rest-to-rest cubic timing along a linear joint-space path $q(s)$ with joint positions and velocities over time.],
    label: <fig:trajectory-example-cubic-lq>,
  )
}
2

I’m not too familiar with lilaq, but I think this is caused by the y-axis labels being of different size (e.g. -0.2pi takes up more space than -2, so the diagram on top is pushed to the right).

After playing around for some time one workaround could be to format the axis, by passing

format-ticks: (ticks, ..args) => {
  let result = lq.format-ticks-linear(ticks, /*suffix: math.pi,*/ ..args)
  ticks.zip(result.labels).map(((tick, label)) => {
    box(width: 2.5em, label)
  })
},

to yaxis, though this has the downside of leaving an ugly gap between the axis and the label. perhaps someone else can come up with a more elegant solution

3

BTW, to format Typst code block in code mode, use typc info string instead of typ.

2 Likes
4

Hi @michi_h!

As @aarnent pointed out, the widths of the diagrams vary due to the different amounts of space that the axes occupy. Normally, you can work around that by applying right-alignment. Here, in combination with subpar, this does not seem to work directly.

You can solve this by replacing columns: 1fr with columns: auto and applying center alignment to the items, for example through

show figure.where(caption: none): set align(right)

This show rule only selects the inner figures not the outer one and you should scope it (i.e. put it inside the #{} and not have it globally).

3 Likes
5

Thanks a lot for the quick help, this works perfectly :)

1 Like