ControlPlots

Introduction

This package provides the following features:

• simple plots can be created with the plot() function
• an oscilloscope-like plot with multiple channels can be created with the plotx() function
• an XY plot can be created with the plotxy() function
• the plot2d function can create fast animations of particle systems, connected with segments
• bode plots using the bode_plot() function
• pan and zoom are supported
• LaTeX can be used for the labels
• the parameters of the plot commands are stored in a struct and returned
• this struct can be displayed again or stored in a file and loaded, the labels etc can be edited and a new plot can be displayed or exported

The goal of this package is to provide simple plots for control system developers and students.

Installation

Usage

Basic example

Launch Julia with julia --project. Then execute: ```julia using ControlPlots, LaTeXStrings

X = 0:0.1:2pi Y = sin.(X) p = plot(X, Y, xlabel=L"\alpha = [0..2\pi]", ylabel="sin", fig="basic") ``` A plot window like this should pop up:

The package LaTeXStrings is only required if you want to use LaTeX for any of your labels like in the example above. You need to prefix LaTeX strings with the letter L.

You can now close the plot window. You can re-display the plot by typing: julia p You can also save the plot under a name of your choice: julia save("plot.jld2", p) Now you restart Julia and load it with: julia using ControlPlots p = load("plot.jld2") The plot is automatically displayed.

Full function signature: julia plot(X, Ys::AbstractVector{<:Union{AbstractVector, Tuple}}; xlabel="", ylabel="", labels=nothing, xlims=nothing, ylims=nothing, ann=nothing, scatter=false, title="", fig="", ysize=14, disp=false)

Running the examples

Create a project folder and start Julia: bash mkdir examples cd examples julia --project=. Add the package, and install and run the examples: julia using Pkg pkg"add ControlPlots" using ControlPlots ControlPlots.install_examples() include("examples/menu.jl") You should now see a menu with all the examples. Select one by using the <UP> and <DOWN> keys and press <ENTER> to run the example.

Multi-channel plot

```julia using ControlPlots

T = 0:0.1:2pi Y1 = sin.(T) Y2 = cos.(T) p = plotx(T, Y1, Y2; ylabels=["Y1", "Y2"], fig="dual") ```

Full function signature: julia plotx(X, Y...; xlabel="time [s]", ylabels=nothing, labels=nothing, xlims=nothing, ylims=nothing, ann=nothing, scatter=false, fig="", title="", ysize=14, legend_size=10, loc="best", yzoom=1.0, bottom=nothing, disp=false) The optional parameter ysize can be used to change the size of the y-axis labels. The default value is 14 points. The optional parameter legend_size can be used to control the font size of the legend. The default value is 10 points. The optional parameter loc can be used to control the legend location. The default value is "best". Other common values include "upper right", "upper left", "lower right", "lower left", "center", etc. The optional parameter bottom can be used to control the bottom margin of the plot when using plt.tight_layout(rect=[0, bottom, 1, 1]). When nothing, the default tight layout is used.

n x m Plot

You can put more than one time series in one or more of the vertically aligned plots, shown before. This is for example useful for combining set value and actual value of a signal in one plot.

```julia using ControlPlots

T = 0:0.1:2pi Y1 = sin.(T) Y2 = 0.2*sin.(2T) Y = cos.(T) plotx(T, [Y1, Y2], Y; ylabels=["sin","cos"], labels=[["Y1","Y2"]], fig="multi-channel-dual", title="multi-channel-dual.jl") `` It is sufficient to pass one or more vectors of time series to theplotx` function. In this case the labels have to be a vector of vectors.

XY-Plot

```julia using ControlPlots

T = 0:0.05:2pi+0.1 X = sin.(T) Y = cos.(3T) p = plotxy(X, Y, xlabel="X", ylabel="Y", fig="xy") ```

n-in-one Plot

You can plot multiple time series in one plot, e.g. like this: ```julia using ControlPlots

x = 1.5*ones(11) y = 1:0.1:2 out = min.(x, y) plot(1:11, [x, y, out]; labels=["inputa", "inputb", "output"], fig="2-in-one") ```

Dual y-axis

```julia using ControlPlots

T = 0:0.05:2pi+0.1 POSZ = sin.(T) VELZ = 5*cos.(T) plot(T, POSZ, VELZ; xlabel="time [s]", ylabels=["posz [m]", "velz [m/s]"], labels=["posz", "velz"], fig="dualy-axis") ```

<img src="./docs/dualy-axis.png" width="400" />

Bode plot

```julia using ControlSystemsBase using ControlPlots

P = tf([1.], [1., 1])

bodeplot(P; from=-2, to=2, title="Low pass filter") ```

<img src="./docs/lowpass_filter.png" width="400" />

Full function signature: julia bode_plot(sys::Union{StateSpace, TransferFunction}; title="", from=-3, to=1, fig=true, db=true, hz=true, bw=false, linestyle="solid", title="", show_title=true, fontsize=18) For using this function you need to do using ControlSystemsBase first, because this is a package extension.

2D video

A video-like display of a particle system (points, connected by lines) can be created with the function plot2d. Example: ```julia using ControlPlots

t = 0 x0 = 2.0 z0 = 0.0 for t in 0:0.1:5 global x0, z0 plot2d([[1,0,0], [x0,0,z0]], t; segments=1) x0 += 0.1; z0 += 0.1 sleep(0.1) end ``` When the function is called at t=0 the line, dot and text objects are created. Each time afterwords these objects are just moved/ updated. Therefore, the update is very fast and you can achieve a high frame rate. With 10 points you can achieve a framerate of 20 Hz or more, depending on the speed of your hardware.

2D video with custom segments

You can create 2D animations with custom line segments between points. Example: ```julia using ControlPlots

for t in 0:0.05:5 # Define points for triangle points = [ [t, 0, 2.0], # top [t-0.5, 0, 1.0], # bottom left [t+0.5, 0, 1.0] # bottom right ]

# Define segments to connect points
segments = [
    [1, 2],  # top to bottom left
    [2, 3],  # bottom left to right
    [3, 1]   # bottom right to top
]

# Plot the triangle
plot2d(points, segments, t; zoom=false, xlim=(0, 5), ylim=(0, 3))
sleep(0.05)

end `` This creates a moving triangle animation. Thesegmentsparameter defines which points should be connected by lines, making it easy to create shapes and animations. Each segment is defined by a pair of indices referring to points in thepoints` array.

Advanced usage

This library uses Matplotlib as backend, and you can change all settings of rcParams as you wish. Example: Using an already installed LaTeX installation for high-quality rendering of LaTeX labels and other text:

More beautiful LaTeX

julia rcParams = plt.PyDict(plt.matplotlib."rcParams") rcParams["text.usetex"] = true Just add this at the beginning of your script. You can change fonts, font sizes, colors etc.

More beautiful GUI

If you add the following line to your .bashrc file or to the script you use to start Julia: bash export MPLBACKEND=qt5agg you get a more beautiful GUI. This does not work on every PC, therefore it is not the default.