Working With Scientific Notation¶

The exponent_format parameter in the theme(...) function can be used to configure the way "exponent notation" looks like on plot.

Available values:

"e" for "e" notation (e.g. 1e+6);
"pow_full" for "power" notation (e.g. $1 \cdot 10^6$). This will enable superscript formatting for the exponent;
"pow" works as "pow_full" but will shorten powers of 10 (e.g. $10^6$ instead of $1 \cdot 10^6$).

The "exponent format" is automatically applied to each value formatted in scientific notation, regardless whether the format is user-defined or chosen automatically based on the data. This format affects every part of a plot, including geoms, scales, labels, and tooltips.

In [1]:

%useLatestDescriptors
%use dataframe
%use lets-plot

In [2]:

LetsPlot.getInfo()

Out[2]:

Lets-Plot Kotlin API v.4.9.0. Frontend: Notebook with dynamically loaded JS. Lets-Plot JS v.4.5.1.

In [3]:

import org.jetbrains.letsPlot.intern.Plot
import org.jetbrains.letsPlot.intern.Scale

In [4]:

val amuCoeffNG = 1.6605402 * 10.0.pow(-15)

In [5]:

val df = DataFrame.readCSV("https://github.com/JetBrains/lets-plot-docs/" +
                           "raw/refs/heads/master/data/chemical_elements.csv").let { df ->
    df["Element", "Symbol", "Type", "Atomic Weight", "Atomic Radius"]
        .rename("Element", "Atomic Weight", "Atomic Radius")
        .into("Name", "Weight (ng)", "Radius")
        .update { "Weight (ng)"<Double>() }.with { amuCoeffNG * it }
}
val dataMap = df.toMap()
df.head()

Out[5]:

DataFrame: rowsCount = 5, columnsCount = 5

Name	Symbol	Type	Radius
Hydrogen	H	Nonmetal	0.790000
Helium	He	Noble Gas	0.490000
Lithium	Li	Alkali Metal	2.100000
Beryllium	Be	Alkaline Earth Metal	1.400000
Boron	B	Metalloid	1.200000

In [6]:

val dMin = -7
val dMax = 6
val values = (dMin..dMax).map { d -> 10.0.pow(d) }

fun hourglassPlot(title: String, numberFormat: String? = null): Plot {
    return letsPlot() { y = values; label = values } +
        geomText(labelFormat = numberFormat, size = 10) +
        scaleYContinuous(limits = Pair(10.0.pow(dMin - 1), 10.0.pow(dMax + 1)),
                         trans = "log10", format = numberFormat) +
        ggtitle(title) +
        themeClassic()
}

In [7]:

val chemicalElementsPlot = letsPlot(dataMap) +
    geomLabel(alpha = .75, fontface = "bold") {
        x = "Weight (ng)"; y = "Radius"; label = "Symbol"; fill = "Type"
    } +
    scaleFillBrewer(guide = guideLegend(ncol = 2)) +
    ggsize(1000, 500) +
    theme(axisTextX = elementText(size = 16, face = "bold"),
          legendKeySize = 12, legendText = elementText(size = 9))
        .legendPosition(.91, .82)

fun formattedXScale(numberFormat: String? = null): Scale {
    return scaleXContinuous(limits = Pair(0.0, 4 * 10.0.pow(-13)),
                            breaks = (0..8).map { (it / 2.0) * 10.0.pow(-13) },
                            format = numberFormat)
}

Default Plot¶

In [8]:

chemicalElementsPlot + formattedXScale()

Out[8]:

Specify Format¶

In [9]:

gggrid(listOf(
    hourglassPlot("Default format"),
    hourglassPlot("format='g'", "g")
))

Out[9]:

In [10]:

chemicalElementsPlot + formattedXScale("g")

Out[10]:

Switch Exponent Format to Power Degree¶

In [11]:

gggrid(listOf(
    hourglassPlot("Default exponentFormat", "g"),
    hourglassPlot("exponentFormat='pow'", "g") + theme(exponentFormat = "pow"),
    hourglassPlot("exponentFormat='pow_full'", "g") + theme(exponentFormat = "pow_full")
))

Out[11]:

In [12]:

chemicalElementsPlot + formattedXScale("g") + theme(exponentFormat = "pow")

Out[12]:

Specify the Limits From Which the Scientific Notation Used¶

In [13]:

gggrid(listOf(
    hourglassPlot("Default limits", "g") + theme(exponentFormat = "pow"),
    hourglassPlot("""Scientific notation for \( x \leq 10^{-3} \) and \( x \geq 10^3 \)""", "g") +
        theme(exponentFormat = listOf("pow", -3, 3))
))

Out[13]:

In [14]:

chemicalElementsPlot + formattedXScale("g") + theme(exponentFormat = listOf("pow", -14, null))

Out[14]: