Implement Scientific Notation in YAML with Python

In this tutorial, you’ll learn how to parse and write scientific notation in YAML using Python.

You’ll explore methods for parsing scientific notation from YAML files, converting these values to Python float objects, and writing them back to YAML while maintaining the desired precision.

 

 

Parse Scientific Notation from YAML

To read YAML files containing scientific notation, you can use the PyYAML library.

Install it using pip install pyyaml if you haven’t already.

import yaml
yaml_content = """
constants:
  planck_constant: 6.62607015e-34
  speed_of_light: 2.99792458e+8
  avogadro_number: 6.02214076e+23
"""
data = yaml.safe_load(yaml_content)
print(data)

Output:

{'constants': {'planck_constant': 6.62607015e-34, 'speed_of_light': 299792458.0, 'avogadro_number': 6.02214076e+23}}

The YAML loader correctly parses the scientific notation values and converts them into Python float objects.

You can now access and use these constants in your calculations.

You can perform calculations using the parsed float values directly. For example, calculating energy using Planck’s constant and the speed of light:

planck_constant = data['constants']['planck_constant']
speed_of_light = data['constants']['speed_of_light']
energy = planck_constant * speed_of_light
print(f"Energy: {energy} J·m")

Output:

Energy: 1.9864458571489286e-25 J·m

The computed energy shows that the scientific notation values from the YAML content are accurate and usable in numerical computations.

 

Write Scientific Notation to YAML

When writing data back to a YAML file, you might want to preserve the scientific notation format. By default, PyYAML maintains the float representation.

import yaml
data_to_dump = {
    'constants': {
        'electron_charge': 1.602176634e-19,
        'boltzmann_constant': 1.380649e-23,
    }
}
yaml_dump = yaml.dump(data_to_dump, default_flow_style=False)
print(yaml_dump)

Output:

constants:
  boltzmann_constant: 1.380649e-23
  electron_charge: 1.602176634e-19

The float values are dumped in scientific notation.

Control precision in YAML scientific notation output

To control the precision of the float values in the YAML output, you can define a custom representer function.

import yaml
from yaml.representer import SafeRepresenter
def float_representer(dumper, value):
    text = '{0:.4e}'.format(value)
    return dumper.represent_scalar('tag:yaml.org,2002:float', text)
yaml.add_representer(float, float_representer)
data_to_dump = {
    'measurements': {
        'light_intensity': 3.1415926535e3,
        'sound_pressure': 2.7182818284e-2,
    }
}
yaml_dump = yaml.dump(data_to_dump, default_flow_style=False)
print(yaml_dump)

Output:

measurements:
  light_intensity: 3.1416e+03
  sound_pressure: 2.7183e-02

 

Create custom YAML representers

To always represent floats in scientific notation, even for regular numbers, you can create a custom representer.

import yaml
def scientific_notation_representer(dumper, value):
    text = '{0:.6e}'.format(value)
    return dumper.represent_scalar('tag:yaml.org,2002:float', text)

yaml.add_representer(float, scientific_notation_representer)
data_to_dump = {
    'data_points': {
        'temperature': 300.0,
        'pressure': 101325.0,
        'volume': 0.0244654037,
    }
}
yaml_dump = yaml.dump(data_to_dump, default_flow_style=False)
print(yaml_dump)

Output:

data_points:
  pressure: 1.013250e+05
  temperature: 3.000000e+02
  volume: 2.446540e-02

This custom representer enforces scientific notation for all float values.