Formatting labels on plots#

In Lets-Plot you can apply a formatting to:

axis break values.
labels displayed by geom_text().
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.

See Formatting documentation page to find information about supported format strings and string templates.

import pandas as pd

from lets_plot import *

LetsPlot.setup_html()

The US Unemployment Rates 2000-2016#

df = pd.read_csv("https://raw.githubusercontent.com/JetBrains/lets-plot-docs/master/data/economics.csv", parse_dates=["date"])
start_date = df["date"].min()
print(df.shape)
df.head()

(574, 7)

	Unnamed: 0	date	pce	pop	psavert	uempmed	unemploy
0	1	1967-07-01	506.7	198712.0	12.6	4.5	2944
1	2	1967-08-01	509.8	198911.0	12.6	4.7	2945
2	3	1967-09-01	515.6	199113.0	11.9	4.6	2958
3	4	1967-10-01	512.2	199311.0	12.9	4.9	3143
4	5	1967-11-01	517.4	199498.0	12.8	4.7	3066

Default plot (no formatting)#

p = ggplot(df, aes("date", "uempmed")) + \
     geom_line() + \
     ylab("unemployment rate") + \
     ggsize(900, 400)

p + scale_x_datetime()

Apply formatting to X and Y axis labels#

Use the format parameter in scale_xxx().

Note that the text in tooltips is now also formatted.

p + \
 scale_x_datetime(format="%b %Y") + \
 scale_y_continuous(format="{} %")

Format axis labels for breaks specified manually#

breaks = pd.date_range(
    pd.to_datetime("2001-01-01"),
    pd.to_datetime("2016-01-01"),
    freq='5YS'
).to_pydatetime()

p + \
 scale_x_datetime(format="%b %Y", breaks=breaks) + \
 scale_y_continuous(format="{} %")

Add the unemployment rate mean#

The geom_text label is formatted using the label_format parameter.

unemployment_mean = df["uempmed"].mean()

ggplot(df, aes("date", "uempmed")) + \
    geom_line(tooltips=layer_tooltips()
                      .line("Unemployment rate:|^y")
                      .anchor('top_center')
                      .min_width(170)) + \
    geom_hline(yintercept=unemployment_mean,
               color="red",
               linetype='dashed',
               tooltips='none') + \
    geom_text(label=unemployment_mean, 
              label_format="{.2f} %",
              x=start_date,
              y=unemployment_mean+.5, 
              color="red") + \
    scale_x_datetime(format="%b %Y") + \
    scale_y_continuous(format="{} %") + \
    ylab("unemployment rate") + \
    ggtitle("The US Unemployment Rates 2000-2016.") + \
    ggsize(900, 400)