Plotting figures and updating in loop

General Usage
,
1

Hi, I want to create plots of a function in a for loop, in separate windows (p1, p2), but it is displayed in a single window.

I used MATLAB and there I used figure (), to create empty figures. in this case I have used plot (), but it does not solve the problem.

this is the code

using Plots 

function sx(E)
    a(x) = x^2 + E 
    b(x) = x + E 
    p1   = plot!(a)
    p2   = plot!(b)
end

E = [12
     24]

p1 = plot()
p2 = plot()

for i = 1:2
    sx(E[i])
end

display(p1)
display(p2)

plots

2

First, the way to update plots is to use plot! with the main plot passed in as its first argument so rewriting your code would look like this:

p1 = plot(title = "Plot 1")
p2 = plot(title = "Plot 2")

function sx(E)
    a(x) = x^2 + E 
    b(x) = x + E 
    plot!(p1, a)
    plot!(p2, b)
end

The default gr() backend doesn’t support multiple windows that I know of but the pyplot backend does by setting reuse=false in p1 and p2 so the full code would look like this:

using Plots 
pyplot() # Switch to the pyplot backend. Needs to be installed first. 

p1 = plot(title = "Plot 1", reuse = false)
p2 = plot(title = "Plot 2", reuse = false)

function sx(E)
    a(x) = x^2 + E 
    b(x) = x + E 
    plot!(p1, a)
    plot!(p2, b)

end

E = [12
     24]


sx.(E) # More Julia way of doing your for loop

p1
p2
2 Likes
3

thanks, but only plot 2 is displayed, plot 1 is not visible

figure
figure1253×584 32.6 KB

4

You need to either evaluate the lines

p1
p2

sequentially or do

display(p1)
p2

if you want two plots in the plot pane. This is because running a code snippet will return whatever the return value of the last line is, and nothing before that.

If you want both plots on one figure you need to do plot(p1, p2).

2 Likes
5

The Julia VSCode extension overrides how plots are displayed. Turning off the VS Code setting julia.usePlotPane will make the plots open in their own window instead of the VS Code plot pane.

Personally, I think you should just plot both in the same window since what your trying to do isn’t really supported by Plots. I wouldn’t expect Julia and Matlab to have the same features or best practices.

plot(p1, p2)

plot(p1, p2, layout=(2,1))

1 Like
6

PyPlot solved the problem using figure(). Thank you for your answers

using PyPlot
figure(1)
plot(xx,yy,color = :red)
plot([x1, x2], [y1, y2],color = :blue)
1 Like