"Plot not defined" when attempting to add slider bars

New to Julia
1

I am learning how to create plots with slider bars. Here is my code based off the first example of this tutorial

function plotLaneEmden(log_delta_xi=-4, n=3)
  fig = Figure()
  
  ax = Axis(fig[1, 1])
  
  sl_x = Slider(fig[2, 1], range = 0:0.01:4.99, startvalue = 3)
  sl_y = Slider(fig[1, 2], range = -6:0.01:0.1, horizontal = false, startvalue = -2)
  
  point = lift(sl_x.value, sl_y.value) do n, log_delta_xi
      Point2f(n, log_delta_xi)
  end
  
  plot(n,  1 .- log_delta_xi.^2/6,  linecolor = :green, label="n = $n")
  
  xlabel!("ξ")
  ylabel!("θ")
end

plotLaneEmden()

When I run this, it gives UndefVarError: plot not defined. What am I missing here?

2

I guess GLMakie doesn’t export a plot function. The example uses scatter!().

3

Ok. I looked at PlutoUI but where in the code do you set up the sliders? How can I adapt this with my code to avoid the same UndefVarError?

4

PlutoUI is a set of functions that wrap HTML input controls to make it easier to create sliders, etc. in a Pluto notebook. You can bind any variable to the slider, and refer to the variable in a plot command, or anywhere else. It won’t solve your problem of using an undefined function. See my notebook for example code.

5

@LeePhillips I got the sliders to work, thanks for sharing your notebook!

There is still a lot about Pluto that confuses me, but we all start somewhere I suppose.

How do you add the value next to the slider by the way?

And how do you set a default value on the slider?

6

To display the value of the slider next to it, just interpolate the variable that it’s bound to right in the Markdown:

md"Time: $tslider  $t  Color: $ccpicker  Line style: $lspicker"

Play with Pluto a bit more and it will click, be patient. It’s fun!

Most controls accept a default argument. I suggest looking through the sample notebooks that are provided when you run Pluto. They’re quite instructive!

1 Like
7

Agreed! re: PlutoUI, their Slider also accepts a show_value keyword, in addition to default, which can be pretty handy

Sort of random, but are you studying stellar physics by any chance @CentraCep? I haven’t seen polytropes in a hot minute!

8

My research area is solar physics, but I completed a course in stellar physics last semester. The program related to this thread was written for fun and to practice Julia, while using something I learned from the class!

9

Cool! Using Julia for some of my own astro related stuff was how I started practicing with Julia as well. Hope you’re enjoying it!