# Add legend titles for distinct categories in Plots

**URL:** <https://discourse.julialang.org/t/add-legend-titles-for-distinct-categories-in-plots/62804>\
**Category:** New to Julia\
**Tags:** plots, pgfplotsx\
**Created:** [June 12, 2021, 6:19pm UTC](https://discourse.julialang.org/t/add-legend-titles-for-distinct-categories-in-plots/62804 "2021-06-12T18:19:04Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![Dan.phi](https://avatars.discourse-cdn.com/v4/letter/d/c89c15/32.png) [@Dan.phi](https://discourse.julialang.org/u/Dan.phi)\
**Post date:** [June 12, 2021, 6:19pm UTC](https://discourse.julialang.org/t/add-legend-titles-for-distinct-categories-in-plots/62804/1 "2021-06-12T18:19:04Z")

</div>

Is it possible to have legend titles for different categories/classes? Something like in the figure below with `continent` and `pop`.

![ggplot2_default_legend_title](https://global.discourse-cdn.com/julialang/original/3X/4/4/4482290a2a7437ce36146cd75622f4b2085368ef.png)

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**Author:** ![rafael.guerra](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/rafael.guerra/32/216610_2.png) [@rafael.guerra](https://discourse.julialang.org/u/rafael.guerra)\
**Post date:** [June 12, 2021, 8:03pm UTC](https://discourse.julialang.org/t/add-legend-titles-for-distinct-categories-in-plots/62804/2 "2021-06-12T20:03:40Z")

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You can use Plots.jl as follows:

(_ **NB:** edited code to be more in line with example provided._)

```julia
using Printf, Plots; pgfplotsx()

n = 2 # number of continents
continents = ["Africa" "Europe"]
ci = ["crimson" "darkgreen"]
x1 = [40 , 50 , 60, 65]; y1 = [1e3,4e3, 5e3, 6.5e3]; p1 = [4e8, 8e8, 11e8, 6e8]
x2 = [60, 70, 80, 85, 90]; y2 = [3e3, 5e3, 9e3, 11e3, 7e3]; p2 = [1e8, 5e8, 7e8, 10e8, 8.5e8]
X = [x1, x2]; Y = [y1, y2]; P = [p1, p2]

m = 4 # number of population ranges
pm = minimum(minimum(P)); pM = maximum(maximum(P))
pr = LinRange(pm,pM,m)
P0 = deepcopy(P)
for p in P0, i in 1:length(p)
    p[i] = pr[argmin(abs.(pr .- p[i]))] # assigns population to one of m-values
end

str = map(x -> @sprintf("%.2g",x), pr)
S = map(x -> x .- pm, P0)
sM = maximum(maximum(S))
md = 3; # minimum dot size
S = map(x -> md .+ 4 * x ./ sM, S)

Xp = [vcat(X...)[vcat(P0...) .== pr[i]] for i in 1:m ]
Yp = [vcat(Y...)[vcat(P0...) .== pr[i]] for i in 1:m ]
Sp = [vcat(S...)[vcat(P0...) .== pr[i]] for i in 1:m ]
X11 = X[1][1]; Y11 = Y[1][1];

PGFPlotsX.enable_interactive(false)
plt = scatter(xlabel="lifeExp", ylabel="gdpPerCap")
scatter!([X11],[Y11],ms=0, mc=:white, label="Population", legend=:outerright, fg_legend=nothing)
scatter!(Xp, Yp, mc=:lightgrey, ms=Sp', label= permutedims(str), colorbar=false)
scatter!([X11], [Y11], ms=0, mc=:white, label=" ")
scatter!([X11], [Y11], ms=0, mc=:white, label="Continent")
[scatter!(X[i]', Y[i]', msc=ci[i], mc=ci[i], ms=S[i]', label=false) for i in 1:n ]
[scatter!([X[i][1]],[Y[i][1]], msc=ci[i], mc=ci[i], ms=md, msw=0, label=continents[i]) for i in 1:n ]
PGFPlotsX.enable_interactive(true)
display(plt)

```

 ![Plots_pgfplotsx_marker_size_legend](https://global.discourse-cdn.com/julialang/original/3X/0/0/00737ce90f43b7c20284f51813c4722e586caf3b.png)

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<div class="post-metadata">

**Author:** ![HerAdri](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/heradri/32/5816_2.png) [@HerAdri](https://discourse.julialang.org/u/HerAdri)\
**Post date:** [June 13, 2021, 4:48am UTC](https://discourse.julialang.org/t/add-legend-titles-for-distinct-categories-in-plots/62804/3 "2021-06-13T04:48:56Z")

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> [@rafael.guerra](#):
>
> ```julia
> using Plots; pgfplotsx()
> 
> n = 2 # number of continents
> x1 = [40 , 50 , 60, 65]; y1 = [1e3,4e3, 5e3, 6.5e3]; p1 = [4e8, 8e8, 11e8, 6e8]
> x2 = [60, 70, 80, 85, 90]; y2 = [3e3, 5e3, 9e3, 11e3, 7e3]; p2 = [1e8, 5e8, 7e8, 10e8, 8.5e8]
> X = [x1, x2]; Y = [y1, y2]; P = [p1, p2]
> pm = minimum(minimum(P)); pM = maximum(maximum(P))
> 
> m = 4 # number of population ranges
> pr = LinRange(pm,pM,m)
> for p in P, i in 1:length(p)
> p[i] = pr[argmin(abs.(pr .- p[i]))]
> end
> 
> str = map(x -> @sprintf("%.2g",x), pr)
> S = map(x -> x .- pm, P)
> sM = maximum(maximum(S))
> S = map(x -> 3 .+ 4 * x ./ sM, S)
> 
> Xp = [vcat(X...)[vcat(P...) .== pr[i]] for i in 1:m ]
> Yp = [vcat(Y...)[vcat(P...) .== pr[i]] for i in 1:m ]
> Sp = [vcat(S...)[vcat(P...) .== pr[i]] for i in 1:m ]
> 
> ci = ["red" "green"]
> continents = ["Africa" "Europe"]
> 
> scatter(xlabel="lifeExp", ylabel="gdpPerCap")
> scatter!([X[1][1]],[Y[1][1]],ms=0, mc=:white,label="pop:",legend=:outertopright)
> scatter!(Xp, Yp, mc=:grey, ms=Sp', label= permutedims(str), colorbar=false)
> scatter!([X[1][1]],[Y[1][1]],ms=0, mc=:white,label=" ")
> scatter!([X[1][1]],[Y[1][1]],ms=0, mc=:white,label="continent:")
> for i in 1:n
> display(scatter!(X[i], Y[i], mc=ci[i], ms=S[i], label=false))
> end
> for i in 1:n
> display(scatter!([X[i][1]],[Y[i][1]], mc=ci[i], ms=3, msw=0, label=continents[i]))
> end
> 
> ```

How to remove these alerts?

```julia
julia> scatter(xlabel="lifeExp", ylabel="gdpPerCap")
Error showing value of type Plots.Plot{Plots.PGFPlotsXBackend}:
ERROR: No LaTeX installation found, figures will not be generated. Make sure either pdflatex or lualatex are installed and that the PATH variable is correctly set.
Stacktrace:
  [1] latexengine()
    @ PGFPlotsX C:\Users\Hermesr\.julia\packages\PGFPlotsX\xJiNw\src\build.jl:19
  [2] show(f::IOBuffer, #unused#::MIME{Symbol("image/svg+xml")}, td::PGFPlotsX.TikzDocument)
    @ PGFPlotsX C:\Users\Hermesr\.julia\packages\PGFPlotsX\xJiNw\src\tikzdocument.jl:289
  [3] _show(io::IOBuffer, mime::MIME{Symbol("image/svg+xml")}, plt::Plots.Plot{Plots.PGFPlotsXBackend})
    @ Plots C:\Users\Hermesr\.julia\packages\Plots\FKcum\src\backends\pgfplotsx.jl:1421
  [4] display(d::VSCodeServer.InlineDisplay, m::MIME{Symbol("image/svg+xml")}, x::Plots.Plot{Plots.PGFPlotsXBackend})
    @ VSCodeServer c:\Users\Hermesr\.vscode\extensions\julialang.language-julia-1.2.3\scripts\packages\VSCodeServer\src\display.jl:0
  [5] display(d::VSCodeServer.InlineDisplay, mime::String, x::Any)
    @ Base.Multimedia .\multimedia.jl:216
  [6] display(d::VSCodeServer.InlineDisplay, x::Plots.Plot{Plots.PGFPlotsXBackend})
    @ VSCodeServer c:\Users\Hermesr\.vscode\extensions\julialang.language-julia-1.2.3\scripts\packages\VSCodeServer\src\display.jl:108
  [7] display(x::Any)
    @ Base.Multimedia .\multimedia.jl:328
  [8] #invokelatest#2
    @ .\essentials.jl:708 [inlined]
  [9] invokelatest
    @ .\essentials.jl:706 [inlined]
 [10] print_response(errio::IO, response::Any, show_value::Bool, have_color::Bool, specialdisplay::Union{Nothing, AbstractDisplay})
    @ REPL C:\buildbot\worker\package_win64\build\usr\share\julia\stdlib\v1.6\REPL\src\REPL.jl:247
 [11] (::REPL.var"#40#41"{REPL.LineEditREPL, Pair{Any, Bool}, Bool, Bool})(io::Any)
    @ REPL C:\buildbot\worker\package_win64\build\usr\share\julia\stdlib\v1.6\REPL\src\REPL.jl:231
 [12] with_repl_linfo(f::Any, repl::REPL.LineEditREPL)
    @ REPL C:\buildbot\worker\package_win64\build\usr\share\julia\stdlib\v1.6\REPL\src\REPL.jl:462
 [13] print_response(repl::REPL.AbstractREPL, response::Any, show_value::Bool, have_color::Bool)
    @ REPL C:\buildbot\worker\package_win64\build\usr\share\julia\stdlib\v1.6\REPL\src\REPL.jl:229
 [14] (::REPL.var"#do_respond#61"{Bool, Bool, REPL.var"#72#82"{REPL.LineEditREPL, REPL.REPLHistoryProvider}, REPL.LineEditREPL, REPL.LineEdit.Prompt})(s::REPL.LineEdit.MIState, buf::Any, ok::Bool)
    @ REPL C:\buildbot\worker\package_win64\build\usr\share\julia\stdlib\v1.6\REPL\src\REPL.jl:798
 [15] #invokelatest#2
    @ .\essentials.jl:708 [inlined]
 [16] invokelatest
    @ .\essentials.jl:706 [inlined]
 [17] run_interface(terminal::REPL.Terminals.TextTerminal, m::REPL.LineEdit.ModalInterface, s::REPL.LineEdit.MIState)
    @ REPL.LineEdit C:\buildbot\worker\package_win64\build\usr\share\julia\stdlib\v1.6\REPL\src\LineEdit.jl:2441
 [18] run_frontend(repl::REPL.LineEditREPL, backend::REPL.REPLBackendRef)
    @ REPL C:\buildbot\worker\package_win64\build\usr\share\julia\stdlib\v1.6\REPL\src\REPL.jl:1126
 [19] (::REPL.var"#44#49"{REPL.LineEditREPL, REPL.REPLBackendRef})()
    @ REPL .\task.jl:411

```

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<div class="post-metadata">

**Author:** ![gustaphe](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/gustaphe/32/18174_2.png) [@gustaphe](https://discourse.julialang.org/u/gustaphe)\
**Post date:** [June 13, 2021, 5:20am UTC](https://discourse.julialang.org/t/add-legend-titles-for-distinct-categories-in-plots/62804/4 "2021-06-13T05:20:15Z")

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Install a LaTeX distribution on your computer. [Get LaTeX - Mac OS, Windows, Linux](https://www.latex-project.org/get/)

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<div class="post-metadata">

**Author:** ![rafael.guerra](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/rafael.guerra/32/216610_2.png) [@rafael.guerra](https://discourse.julialang.org/u/rafael.guerra)\
**Post date:** [June 13, 2021, 1:53pm UTC](https://discourse.julialang.org/t/add-legend-titles-for-distinct-categories-in-plots/62804/5 "2021-06-13T13:53:48Z")

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@HerAdri, fyi, running Julia 1.6.1 on Win10 with [MiKTeX](https://miktex.org/) installed.  
Thanks @gustaphe.

_ **NB:** edited code above to be more user friendly_