Calculate Pi with Dash

dash_pi.jl

using HTTP
using Dashboards
using PlotlyJS

function compute_pi(N::Int)
   n_landed_in_circle = 0  
   for i = 1:N
       x = rand() * 2 - 1  
       y = rand() * 2 - 1  
       r2 = x*x + y*y 
       if r2 < 1.0
           n_landed_in_circle += 1
       end
   end
   return n_landed_in_circle / N * 4.0
end

app = Dash("Pi App", external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"]) do
   html_div() do
     html_h2("Calculate the Value of Pi"),
     dcc_slider(id="num_iterations", min=10000, max=100000, step=1000, marks=Dict(Symbol(i)=>Symbol(i) for i in 10000:10000:100000), value=20000),
     html_br(),
     html_button("Pi!", id="submit_button", n_clicks=0),
     html_div() do
       html_span("Pi = "),
       html_span("0.0", id="pi")
     end,
     dcc_graph(id="pi_graph")
   end
end;

callback!(app, callid"{num_iterations.value} submit_button.n_clicks => pi.children, pi_graph.figure") do N, c
  a = [compute_pi(n) for n in 1:1000:20000]
  return a[end], Plot(a,
           Layout(;xaxis_title = "Iterations",
                  yaxis_title = "Pi",
                  legend_x = 0,
                  legend_y = 1
                  );
                  x = collect(1:1000:10000),
                  )
end

h = make_handler(app, debug=true)
HTTP.serve(h, "127.0.0.1", 8080)