arithmetic-expressions

arithmetic-expression is a Python module for symbolic arithmetic expressions. It supports serialization, deserialization, evaluation with custom variables, and an easy construction interface by combining existing expressions.

It is built around Python's ast module and therefore uses Python syntax when string serializing and deserializing. However, it only supports single-line expressions and strongly restricts the grammar when evaluating expressions. This constrained subset of the grammar encompasses variables, numeric constants, unary and binary arithmetic operators, comparison operators, the ternary if-else operator and selected function calls.

Expressions can be deserialized from strings, but can also be built from scratch with an intuitive API that aligns with Python's own syntax.

Example

from arithmetic_expressions import Expression

# Parse an expression
Expression.parse("x * 2 + 1")

# Or create it from scratch
expression = Expression("x") * 2 + 1

# String casting will serialize the expression
print(expression)  # prints "x * 2 + 1"

# Pass variables to evaluate it
print(expression.evaluate(x=3))  # prints "7"