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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.

Note

Superscript is not supported when exporting to PNG/PDF.

In [1]:
import pandas as pd

from lets_plot import *
In [2]:
LetsPlot.setup_html()
In [3]:
amu_coeff_ng = 1.6605402 * 10**(-15)
In [4]:
df = pd.read_csv("https://github.com/JetBrains/lets-plot-docs/raw/refs/heads/master/data/chemical_elements.csv", \
                 encoding_errors='backslashreplace')
df = df[["Element", "Symbol", "Type", "Atomic Weight", "Atomic Radius"]]
df.columns = ["Name", "Symbol", "Type", "Weight (ng)", "Radius"]
df["Weight (ng)"] *= amu_coeff_ng
print(df.shape)
df.head()

(118, 5)
Out[4]:
Name Symbol Type Weight (ng) Radius
0 Hydrogen H Nonmetal 1.673725e-15 0.79
1 Helium He Noble Gas 6.646482e-15 0.49
2 Lithium Li Alkali Metal 1.152581e-14 2.10
3 Beryllium Be Alkaline Earth Metal 1.496509e-14 1.40
4 Boron B Metalloid 1.795210e-14 1.20
In [5]:
def small_example(title, number_format=None):
    dmin, dmax = -7, 6
    values = [10**d for d in range(dmin, dmax + 1)]
    return ggplot() + \
        geom_text(aes(y=values, label=values), label_format=number_format, size=12) + \
        scale_y_continuous(limits=[10**(dmin - 1), 10**(dmax + 1)], trans='log10', format=number_format) + \
        ggtitle(title) + \
        theme_classic()
In [6]:
def plot(number_format=None):
    return ggplot(df) + \
        geom_label(aes("Weight (ng)", "Radius", label="Symbol", fill="Type"), alpha=.75, fontface='bold') + \
        scale_x_continuous(limits=[0, 4*10**(-13)], \
                           breaks=[(i / 2.0)*10**(-13) for i in range(9)], \
                           format=number_format) + \
        scale_fill_brewer(guide=guide_legend(ncol=2)) + \
        ggsize(1000, 500) + \
        theme(axis_text_x=element_text(size=16, face='bold'), \
              legend_position=(.91, .89), legend_key_size=12, legend_text=element_text(size=9))

Default Plot

In [7]:
plot()
Out[7]:

Specify Format

In [8]:
gggrid([
    small_example("Default format"),
    small_example("format='g'", "g")
])
Out[8]:
In [9]:
plot(number_format="g")
Out[9]:

Switch Exponent Format to Power Degree

In [10]:
gggrid([
    small_example("Default exponent_format", "g"),
    small_example("exponent_format='pow'", "g") + theme(exponent_format='pow'),
    small_example("exponent_format='pow_full'", "g") + theme(exponent_format='pow_full')
])
Out[10]:
In [11]:
plot("g") + theme(exponent_format='pow')
Out[11]:

Specify the Limits From Which the Scientific Notation Used

In [12]:
gggrid([
    small_example("Default limits", "g") + theme(exponent_format='pow'),
    small_example("Scientific notation for \( x \leq 10^{-3} \) and \( x \geq 10^3 \)", "g") + \
        theme(exponent_format=('pow', -3, 3))
])
Out[12]:
In [13]:
plot("g") + theme(exponent_format=('pow', -14, None))
Out[13]: