forallpeople documentation

“For all time. For all people.” - Nicolas de Caritat (Marquis de Condorcet), in regards to the metric system (now the SI system)

forallpeople is a Python library for representing the SI base units to enable easy-to-use, units-aware calculations. In addition to the SI base units, forallpeople can be used to represent units which are defined by the SI unit system, such as US Customary units.

Installation

pip install forallpeople

A Simple Example

import forallpeople as si
si.environment('default')

g = 9.81 * si.m/si.s**2
m = 3500 * si.kg
force = m * g
force

34.335 kN

Features

• Rich representations for use in Jupyter (HTML, Latex, plain-text)

• Units display as conventional symbols by default

• Units “auto-reduce” based upon the unit environment

• Auto-scaling of SI derived units and base units (e.g. 1100 Hz -> 1.1 kHz)

• Conversion between units defined in your environment

• Custom unit environments for defining US, imperial, and derived SI unit options

• Interactive imports to push unit names into the top level namespace

• Immutable, hashable instances

Contents

• Basic Usage
  • Module-level import
  • Interactive import
  • String formatting
• API
  • API
    • Physical
      • Physical.prefix()
      • Physical.repr
      • Physical.split()
      • Physical.to()
• Standard Behaviours
  • 1. Conventional Arithmetic
  • 2. Auto-scaling of base units and derived units
  • 3. Three-decimals precision
  • 4. Unit cancellation
  • 5. Conversion to float and int
  • 6. Using math functions
  • 7. Using Floor and Modulo
• Dimensionally-inconsistent Calculations
  • Dimensionally-inconsistent radicals
    • Strategy 1 - Manually add the units back on
    • Strategy 2 - Define a custom sqrt function
    • Strategy 3
  • Hidden units
  • Completely inconsistent formulae
• Customizing Environments
  • Definitions:
  • Loading Environments
    • Bundled environments
    • Inspecting environments
  • Environment files
    • Customizing your environments (making new environment files)
    • Unit Resolution
• Background and Approach
  • Data Model
  • Unit Representation
  • No dimensionless definitions
  • Auto-scaling