Customize Legend Appearance¶

In [1]:

%useLatestDescriptors
%use dataframe
%use lets-plot

In [2]:

import javax.imageio.ImageIO

ImageIO.read(File("images/theme_legend_scheme.png"))

Out[2]:

In [3]:

val df = DataFrame.readCSV("https://raw.githubusercontent.com/JetBrains/lets-plot-docs/master/data/mpg.csv")
val dataMap = df.toMap()
df.head(3)

Out[3]:

DataFrame: rowsCount = 3, columnsCount = 12

untitled	manufacturer	model	displ	year	cyl	trans	drv	cty	hwy	fl	class
1	audi	a4	1.800000	1999	4	auto(l5)	f	18	29	p	compact
2	audi	a4	1.800000	1999	4	manual(m5)	f	21	29	p	compact
3	audi	a4	2.000000	2008	4	manual(m6)	f	20	31	p	compact

Legend Position¶

Parameters to customize the legend position and justification:

legendPosition - the position of legends;
legendJustification - anchor point for positioning legend;
legendDirection - layout of items in legends.

In [4]:

val p1 = letsPlot(dataMap) { x = "displ"; y = "hwy" } +
    geomPoint(size = 5) { color = "cty"; shape = "drv" }
p1

Out[4]:

In [5]:

// Draw legend below the plot area
p1 + theme().legendPositionBottom()

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In [6]:

// Specify position, justification and orientation
p1 + theme().legendPosition(1, 1).legendJustification(1, 1).legendDirectionHorizontal()

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Legend Spacing and Margins¶

Parameters to customize the legend spacing and margins:

legendBoxSpacing - spacing between plotting area and legend box;
legendMargin - margin around each legend;
legendSpacing - spacing between legends, legendSpacingX/legendSpacingY - in the horizontal/vertical direction.

Arrangement of multiple legends:

fun legendBoxHorizontal();
fun legendBoxVertical().

Justification of each legend within the overall bounding box:

fun legendBoxJustificationLeft();
fun legendBoxJustificationRight();
fun legendBoxJustificationTop();
fun legendBoxJustificationBottom();
fun legendBoxJustificationCenter().

In [7]:

val p2 = letsPlot(dataMap) { x = "displ"; y = "cty" } +
    geomPoint(shape = 21) { fill = "drv"; size = "hwy" } +
    scaleSize(range = 1 to 10, breaks = listOf(15, 30, 40)) +
    theme(legendBackground = elementRect(size = 1)).legendPositionBottom()
p2

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`legendMargin`¶

In [8]:

p2 + theme(legendMargin = listOf(10, 20))

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Arrangement in Legend Box¶

In [9]:

p2 + theme().legendBoxHorizontal()

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Legend Justification within Overall Bounding Box¶

In [10]:

p2 + theme().legendBoxJustificationCenter()

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`legendBoxSpacing`¶

In [11]:

p2 + theme(legendBoxSpacing = 50).legendBoxHorizontal()

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`legendSpacing`¶

In [12]:

p2 + theme(legendSpacing = 50).legendBoxHorizontal()

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Legend Key Parameters¶

Parameters to customize the legend key:

legendKey - background underneath legend keys, set with elementRect();
legendKeySize - size of legend keys;
legendKeyWidth - key background width;
legendKeyHeight - key background height;
legendKeySpacing - spacing between legend keys;
legendKeySpacingX - spacing in the horizontal direction;
legendKeySpacingY - spacing in the vertical direction.

In [13]:

val p3 = letsPlot(dataMap) { x = "hwy" } +
    geomDotplot(color="pen") { fill = "class" } +
    theme(legendBackground = elementRect(size = 0.5))
p3

Out[13]:

Add background underneath legend keys:

In [14]:

val p4 = p3 + theme(legendKey = elementRect(fill = "#efedf5", color = "#756bb1"))
p4

Out[14]:

Change size of legend keys:

In [15]:

p4 + theme(legendKeySize = 30)

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In [16]:

val p5 = p4 + theme(legendKeyWidth = 80, legendKeyHeight = 20)
p5

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Add spacing between legend keys:

In [17]:

p5 + theme(legendKeySpacingY = 10)

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