Legend

Creating A Legend From Elements

You can create a basic Legend by passing a vector of legend entries and a vector of labels, plus an optional title as the third argument.

The elements in the vector of legend entries can either be plot objects or LegendElements like LineElement, MarkerElement and PolyElement. Or they can be vectors of such objects that will be layered together as one.

Legend element attributes

The standard plot objects like Scatter or Lines have predefined conversions to MarkerElements and LineElements that copy the relevant plot attributes to the legend element. If an attribute has a vector-like value, it falls back to the scalar default of the legend. The legend defaults themselves are by default inherited from the main theme. For example, polystrokewidth of the legend falls back to patchstrokewidth of the main theme. In the following example, you can see that the legend for sca2 copies the :rect marker but not the vector-valued color.

using CairoMakie

f = Figure()

Axis(f[1, 1])

xs = 0:0.5:10
ys = sin.(xs)
lin = lines!(xs, ys, color = :blue)
sca = scatter!(xs, ys, color = :red)
sca2 = scatter!(xs, ys .+ 0.5, color = 1:length(xs), marker = :rect)

Legend(f[1, 2],
    [lin, sca, [lin, sca], sca2],
    ["a line", "some dots", "both together", "rect markers"])

f

Creating A Legend From An Axis

You can also create a Legend by passing it an axis object, like Axis, LScene or Scene. All plots that have a label attribute set will be put into the legend, in the order that they appear in the axis, and you can optionally pass a title as the third argument.

using CairoMakie

f = Figure()

ax = f[1, 1] = Axis(f)

lines!(0..15, sin, label = "sin", color = :blue)
lines!(0..15, cos, label = "cos", color = :red)
lines!(0..15, x -> -cos(x), label = "-cos", color = :green)

f[1, 2] = Legend(f, ax, "Trig Functions", framevisible = false)

f

With the keywords merge and unique you can control how plot objects with the same labels are treated. If merge is true, all plot objects with the same label will be layered on top of each other into one legend entry. If unique is true, all plot objects with the same plot type and label will be reduced to one occurrence.

using CairoMakie

f = Figure()

traces = cumsum(randn(10, 5), dims = 1)

for (i, (merge, unique)) in enumerate(
        Iterators.product([false, true], [false true]))

    axis = Axis(f[fldmod1(i, 2)...],
        title = "merge = $merge, unique = $unique")

    for trace in eachcol(traces)
        lines!(trace, label = "single", color = (:black, 0.2))
    end

    mu = vec(sum(traces, dims = 2) ./ 5)
    lines!(mu, label = "mean")
    scatter!(mu, label = "mean")

    axislegend(axis, merge = merge, unique = unique)

end

f

Legend Inside An Axis

The axislegend function is a quick way to add a legend to an Axis. You can pass a selected axis plus arguments which are forwarded to the Legend constructor, or the current axis is used by default. If you pass only a string, it's used as the title with the current axis.

The position can be set via a shortcut symbol, first halign (l, r, c) then valign (b, t, c), such as :lt for left, top and :cb for center bottom.

using CairoMakie

f = Figure()

ax = Axis(f[1, 1])

sc1 = scatter!(randn(10, 2), color = :red, label = "Red Dots")
sc2 = scatter!(randn(10, 2), color = :blue, label = "Blue Dots")
scatter!(randn(10, 2), color = :orange, label = "Orange Dots")
scatter!(randn(10, 2), color = :cyan, label = "Cyan Dots")

axislegend()

axislegend("Titled Legend", position = :lb)

axislegend(ax, [sc1, sc2], ["One", "Two"], "Selected Dots", position = :rb,
    orientation = :horizontal)

f

Alternatively, you can simply add a Legend to the same layout slot that an axis lives in. As long as the axis is bigger than the legend you can set the legend's tellheight and tellwidth to false and position it using the align variables. You can use the margin keyword to keep the legend from touching the axis spines.

using CairoMakie

haligns = [:left, :right, :center]
valigns = [:top, :bottom, :center]

f = Figure()

Axis(f[1, 1])

xs = 0:0.1:10
lins = [lines!(xs, sin.(xs .* i), color = color)
    for (i, color) in zip(1:3, [:red, :blue, :green])]

for (j, ha, va) in zip(1:3, haligns, valigns)
    Legend(
        f[1, 1], lins, ["Line $i" for i in 1:3],
        "$ha & $va",
        tellheight = false,
        tellwidth = false,
        margin = (10, 10, 10, 10),
        halign = ha, valign = va, orientation = :horizontal
    )
end

f

Creating Legend Entries Manually

Sometimes you might want to construct legend entries from scratch to have maximum control. So far you can use LineElements, MarkerElements or PolyElements. The attributes for these elements are the following (the [] parts can be left out when constructing these elements directly, but have to be fully written out for the attributes that the legend holds):

# LineElement
[line]points, [line]color, linestyle, linewidth

# MarkerElement
[marker]points, marker, markersize, [marker]color,
[marker]strokewidth, [marker]strokecolor

# PolyElement
[poly]points, [poly]color, [poly]strokewidth, [poly]strokecolor

The attributes linepoints, markerpoints and polypoints decide where in the legend entry patch rectangle the plot objects are placed. These values should be normalized to a 1 by 1 rectangle, and the final shape depends on the patchsize of the legend. For example, if you want wider line and poly markers, you could set the patchsize of the legend to (50, 30).

using CairoMakie

f = Figure()

Axis(f[1, 1])

elem_1 = [LineElement(color = :red, linestyle = nothing),
          MarkerElement(color = :blue, marker = 'x', markersize = 15,
          strokecolor = :black)]

elem_2 = [PolyElement(color = :red, strokecolor = :blue, strokewidth = 1),
          LineElement(color = :black, linestyle = :dash)]

elem_3 = LineElement(color = :green, linestyle = nothing,
        points = Point2f[(0, 0), (0, 1), (1, 0), (1, 1)])

elem_4 = MarkerElement(color = :blue, marker = 'π', markersize = 15,
        points = Point2f[(0.2, 0.2), (0.5, 0.8), (0.8, 0.2)])

elem_5 = PolyElement(color = :green, strokecolor = :black, strokewidth = 2,
        points = Point2f[(0, 0), (1, 0), (0, 1)])

Legend(f[1, 2],
    [elem_1, elem_2, elem_3, elem_4, elem_5],
    ["Line & Marker", "Poly & Line", "Line", "Marker", "Poly"],
    patchsize = (35, 35), rowgap = 10)

f

Multi-Group Legends

Sometimes a legend consists of multiple groups, for example in a plot where both marker size and color are varied and those properties need to be visualized separately, but still together in one legend. Each group's content is given as an array of elements and an array of labels, each within one collective array. You can shift the position of the titles relative to each group with the titleposition attribute, either :left or :top.

using CairoMakie

f = Figure()

markersizes = [5, 10, 15, 20]
colors = [:red, :green, :blue, :orange]

group_size = [MarkerElement(marker = :circle, color = :black,
    strokecolor = :transparent,
    markersize = ms) for ms in markersizes]

group_color = [PolyElement(color = color, strokecolor = :transparent)
    for color in colors]

legends = [Legend(f,
    [group_size, group_color],
    [string.(markersizes), string.(colors)],
    ["Size", "Color"], tellheight = true) for _ in 1:4]

f[1, 1:2] = legends[1:2]
f[2, :] = legends[3]
f[3, :] = legends[4]

for l in legends[3:4]
    l.orientation = :horizontal
    l.tellheight = true
    l.tellwidth = false
end

legends[2].titleposition = :left
legends[4].titleposition = :left

legends[1].nbanks = 2
legends[4].nbanks = 2

Label(f[1, 1, Left()], "titleposition = :top\norientation = :vertical\nnbanks = 2", font = :italic, padding = (0, 10, 0, 0))
Label(f[1, 2, Right()], "titleposition = :left\norientation = :vertical\nnbanks = 1", font = :italic, padding = (10, 0, 0, 0))
Label(f[2, 1:2, Top()], "titleposition = :top, orientation = :horizontal\nnbanks = 1", font = :italic)
Label(f[3, 1:2, Top()], "titleposition = :left, orientation = :horizontal\nnbanks = 2", font = :italic)

f

Attributes

`alignmode`

Defaults to Inside()

The align mode of the legend in its parent GridLayout.

`backgroundcolor`

Defaults to :white

The background color of the legend.

`bgcolor`

Defaults to nothing

The background color of the legend. DEPRECATED - use backgroundcolor instead.

`colgap`

Defaults to 16

The gap between the label of one legend entry and the patch of the next.

Example: Column gaps

using CairoMakie
fig = Figure()
ax = Axis(fig[1, 1])
lines!(ax, 1:10, linestyle = :dash, label = "Line")
poly!(ax, [(5, 0), (10, 0), (7.5, 5)], label = "Poly")
scatter!(ax, 4:13, label = "Scatter")
Legend(fig[1, 2], ax, "Default", nbanks = 2)
Legend(fig[1, 3], ax, "colgap = 40", nbanks = 2, colgap = 40)
fig

`framecolor`

Defaults to :black

The color of the legend border.

`framevisible`

Defaults to true

Controls if the legend border is visible.

`framewidth`

Defaults to 1.0

The line width of the legend border.

`gridshalign`

Defaults to :center

The horizontal alignment of entry groups in their parent GridLayout.

`gridsvalign`

Defaults to :center

The vertical alignment of entry groups in their parent GridLayout.

`groupgap`

Defaults to 16

The gap between each group and the next.

Example: Group gaps

using CairoMakie
fig = Figure()
ax = Axis(fig[1, 1])
lin = lines!(ax, 1:10, linestyle = :dash)
pol = poly!(ax, [(5, 0), (10, 0), (7.5, 5)])
sca = scatter!(ax, 4:13)
Legend(fig[1, 2],
    [[lin], [pol], [sca]],
    [["Line"], ["Poly"], ["Scatter"]],
    ["Default", "Group 2", "Group 3"];

)
Legend(fig[1, 3],
    [[lin], [pol], [sca]],
    [["Line"], ["Poly"], ["Scatter"]],
    ["groupgap = 30", "Group 2", "Group 3"];
    groupgap = 30,
)
fig

`halign`

Defaults to :center

The horizontal alignment of the legend in its suggested bounding box.

`height`

Defaults to Auto()

The height setting of the legend.

`label`

Defaults to "undefined"

The default entry label.

`labelcolor`

Defaults to @inherit :textcolor :black

The color of the entry labels.

`labelfont`

Defaults to :regular

The font family of the entry labels.

`labelhalign`

Defaults to :left

The horizontal alignment of the entry labels.

`labeljustification`

Defaults to automatic

The justification of the label text. Default is automatic, which will set the justification to labelhalign.

`labelsize`

Defaults to @inherit :fontsize 16.0f0

The font size of the entry labels.

`labelvalign`

Defaults to :center

The vertical alignment of the entry labels.

`linecolor`

Defaults to theme(scene, :linecolor)

The default line color used for LineElements

`linecolormap`

Defaults to theme(scene, :colormap)

The default colormap for LineElements

`linecolorrange`

Defaults to automatic

The default colorrange for LineElements

`linepoints`

Defaults to [Point2f(0, 0.5), Point2f(1, 0.5)]

The default points used for LineElements in normalized coordinates relative to each label patch.

`linestyle`

Defaults to :solid

The default line style used for LineElements

`linewidth`

Defaults to theme(scene, :linewidth)

The default line width used for LineElements.

`margin`

Defaults to (0.0f0, 0.0f0, 0.0f0, 0.0f0)

The additional space between the legend and its suggested boundingbox.

`marker`

Defaults to theme(scene, :marker)

The default marker for MarkerElements

`markercolor`

Defaults to theme(scene, :markercolor)

The default marker color for MarkerElements

`markercolormap`

Defaults to theme(scene, :colormap)

The default marker colormap for MarkerElements

`markercolorrange`

Defaults to automatic

The default marker colorrange for MarkerElements

`markerpoints`

Defaults to [Point2f(0.5, 0.5)]

The default marker points used for MarkerElements in normalized coordinates relative to each label patch.

`markersize`

Defaults to theme(scene, :markersize)

The default marker size used for MarkerElements.

`markerstrokecolor`

Defaults to theme(scene, :markerstrokecolor)

The default marker stroke color used for MarkerElements.

`markerstrokewidth`

Defaults to theme(scene, :markerstrokewidth)

The default marker stroke width used for MarkerElements.

`nbanks`

Defaults to 1

The number of banks in which the legend entries are grouped. Columns if the legend is vertically oriented, otherwise rows.

Example: Number of banks with `orientation = :vertical`

using CairoMakie
fig = Figure()
ax = Axis(fig[1, 1])
lines!(ax, 1:10, linestyle = :dash, label = "Line")
poly!(ax, [(5, 0), (10, 0), (7.5, 5)], label = "Poly")
scatter!(ax, 4:13, label = "Scatter")
grid = GridLayout(fig[1, 2], tellheight = false)
Legend(grid[1, 1], ax, "nbanks = 1", nbanks = 1, tellheight = true)
Legend(grid[1, 2], ax, "nbanks = 2", nbanks = 2, tellheight = true)
Legend(grid[2, :], ax, "nbanks = 3", nbanks = 3, tellheight = true)
fig

Example: Number of banks with `orientation = :horizontal`

using CairoMakie
fig = Figure()
ax = Axis(fig[1, 1])
lines!(ax, 1:10, linestyle = :dash, label = "Line")
poly!(ax, [(5, 0), (10, 0), (7.5, 5)], label = "Poly")
scatter!(ax, 4:13, label = "Scatter")
grid = GridLayout(fig[2, 1], tellwidth = false)
Legend(grid[1, 1], ax, "nbanks = 1", nbanks = 1,
    orientation = :horizontal, tellwidth = true)
Legend(grid[2, 1], ax, "nbanks = 2", nbanks = 2,
    orientation = :horizontal, tellwidth = true)
Legend(grid[:, 2], ax, "nbanks = 3", nbanks = 3,
    orientation = :horizontal, tellwidth = true)
fig

`orientation`

Defaults to :vertical

The orientation of the legend (:horizontal or :vertical).

Example: Orientations

using CairoMakie
fig = Figure()
ax = Axis(fig[1, 1])
lines!(ax, 1:10, linestyle = :dash, label = "Line")
poly!(ax, [(5, 0), (10, 0), (7.5, 5)], label = "Poly")
scatter!(ax, 4:13, label = "Scatter")
Legend(fig[2, 1], ax, "orientation
= :horizontal", orientation = :horizontal)
Legend(fig[1, 2], ax, "orientation
= :vertical", orientation = :vertical)
fig

`padding`

Defaults to (6.0f0, 6.0f0, 6.0f0, 6.0f0)

The additional space between the legend content and the border.

`patchcolor`

Defaults to :transparent

The color of the patches containing the legend markers.

`patchlabelgap`

Defaults to 5

The gap between the patch and the label of each legend entry.

Example: Gap sizes

using CairoMakie
fig = Figure()
ax = Axis(fig[1, 1])
lines!(ax, 1:10, linestyle = :dash, label = "Line")
poly!(ax, [(5, 0), (10, 0), (7.5, 5)], label = "Poly")
scatter!(ax, 4:13, label = "Scatter")
Legend(fig[1, 2], ax, "Default")
Legend(fig[1, 3], ax, "patchlabelgap
= 20", patchlabelgap = 20)
fig

`patchsize`

Defaults to (20.0f0, 20.0f0)

The size of the rectangles containing the legend markers. It can help to increase the width if line patterns are not clearly visible with the default size.

Example: Patch size

using CairoMakie
fig = Figure()
ax = Axis(fig[1, 1])
lines!(ax, 1:10, linestyle = :dash, label = "Line")
poly!(ax, [(5, 0), (10, 0), (7.5, 5)], label = "Poly")
scatter!(ax, 4:13, label = "Scatter")
Legend(fig[1, 2], ax, "Default")
Legend(fig[1, 3], ax, "(40, 20)", patchsize = (40, 20))
fig

using CairoMakie
fig = Figure()
ax = Axis(fig[1, 1])
lines!(ax, 1:10, linestyle = :dash, label = "Line")
poly!(ax, [(5, 0), (10, 0), (7.5, 5)], label = "Poly")
scatter!(ax, 4:13, label = "Scatter")
Legend(fig[1, 2], ax, "Default")
Legend(fig[1, 3], ax, "rowgap = 10", rowgap = 10)
fig

using CairoMakie
fig = Figure()
ax = Axis(fig[1, 1])
lines!(ax, 1:10, linestyle = :dash, label = "Line")
poly!(ax, [(5, 0), (10, 0), (7.5, 5)], label = "Poly")
scatter!(ax, 4:13, label = "Scatter")
Legend(fig[1, 2], ax, "titleposition
= :top", titleposition = :top)
Legend(fig[1, 3], ax, "titleposition
= :left", titleposition = :left)
fig

These docs were autogenerated using Makie: v0.20.9, GLMakie: v0.9.10, CairoMakie: v0.11.10, WGLMakie: v0.9.9