Formatting labels on plots.¶

In Lets-Plot you can apply a formatting to:

axis break values.
labels displayed by geomText().
tooltip text.
facet labels.

Using format string you can format values of numeric and date-time types.

In addition, you can use a string template.

In string template the value's format string is surrounded by curly braces: "... {.2f} ...".

An empty placeholder {} is also allowed. In this case a default string representation will be shown. This is also applicable to categorical values.

To learn more about formatting templates see: Formatting.

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.

The US Unemployment Rates 2000-2016¶

In [3]:

var economics = DataFrame.readCSV("https://vincentarelbundock.github.io/Rdatasets/csv/ggplot2/economics.csv")

In [4]:

economics.head()

Out[4]:

DataFrame: rowsCount = 5, columnsCount = 7

rownames	date	pce	pop	psavert	uempmed	unemploy
1	1967-07-01	506.700000	198712.000000	12.600000	4.500000	2944
2	1967-08-01	509.800000	198911.000000	12.600000	4.700000	2945
3	1967-09-01	515.600000	199113.000000	11.900000	4.600000	2958
4	1967-10-01	512.200000	199311.000000	12.900000	4.900000	3143
5	1967-11-01	517.400000	199498.000000	12.800000	4.700000	3066

In [5]:

import kotlinx.datetime.*

fun LocalDate.toEpochMilliseconds(): Long {
    return atStartOfDayIn((TimeZone.currentSystemDefault())).toEpochMilliseconds()
}

In [6]:

val startDate = LocalDate.parse("2000-01-01")
economics = economics.filter { date.compareTo(startDate) >= 0 }.convert {date}.with {it.toEpochMilliseconds()}

In [7]:

val p = letsPlot(economics.toMap()){x="date"; y="uempmed"} + 
    geomLine() +
    ylab("unemployment rate") +
    ggsize(900, 400)

Default plot (no formatting)¶

Apply formatting to X and Y axis labels.¶

Use the format parameter in scaleXxx().

Note that the text in tooltips is now also formatted.

In [8]:

p + scaleXDateTime(format="%b %Y") + scaleYContinuous(format="{} %")

Out[8]:

Format axis labels for breaks specified manually¶

In [9]:

val breaks = listOf(
    LocalDate.parse("2001-01-01"), 
    LocalDate.parse("2016-01-01")
).map {it.toEpochMilliseconds()}

p + scaleXDateTime(format="%b %Y", breaks=breaks) + scaleYContinuous(format="{} %")

Out[9]:

Configure tooltip's text and location.¶

In [10]:

letsPlot(economics.toMap()){x="date"; y="uempmed"} + 
 geomLine(tooltips=layerTooltips()
        .line("Unemployment rate:|^y")
        .anchor("top_center")
        .minWidth(170)) + 
 scaleXDateTime(format="%b %Y") +
 scaleYContinuous(format="{} %") +
 ylab("unemployment rate") +
 ggsize(900, 400)

Out[10]:

Format value shown in tooltip.¶

In [11]:

letsPlot(economics.toMap()){x="date"; y="uempmed"} +
 geomLine(tooltips=layerTooltips()
               .line("@uempmed % in @date")
               .format("date", "%B %Y")
               .anchor("top_left")
               .minWidth(170)) +
 scaleXDateTime() +
 scaleYContinuous() +
 ylab("unemployment rate") +
 ggsize(900, 400)

Out[11]:

Add the unemployment rate mean.¶

The geomText label is formatted using the labelFormat parameter.

In [12]:

val unemploymentMean = economics.uempmed.mean()


letsPlot(economics.toMap()){x="date"; y="uempmed"} + 
 geomLine(tooltips=layerTooltips()
        .line("Unemployment rate:|^y %")
        .anchor("top_center")
        .minWidth(170)) + 
 geomHLine(yintercept=unemploymentMean, color="red", linetype="dashed", tooltips=tooltipsNone) +
 geomText(label=unemploymentMean.toString(), 
           labelFormat="{.2f} %",
           x=startDate.toEpochMilliseconds(), y=unemploymentMean!! + 0.5, 
           color="red") +
 scaleXDateTime(format="%b %Y") + 
 scaleYContinuous(format="{} %") + 
 ylab("unemployment rate") +
 ggtitle("The US Unemployment Rates 2000-2016.") +
 ggsize(900, 400)

Out[12]: