https://github.com/pyparsing/plusminus
https://github.com/pyparsing/plusminus
arithmetic-expression-evaluator evaluate-expressions infix-evaluation infix-expression-parser infix-notation parsing parsing-library python python-3 python3 python3-library safe-evaluation
Last synced: about 1 month ago
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- Host: GitHub
- URL: https://github.com/pyparsing/plusminus
- Owner: pyparsing
- License: mit
- Created: 2019-12-25T16:09:56.000Z (over 5 years ago)
- Default Branch: master
- Last Pushed: 2024-10-11T13:18:01.000Z (7 months ago)
- Last Synced: 2025-04-15T06:55:42.977Z (about 1 month ago)
- Topics: arithmetic-expression-evaluator, evaluate-expressions, infix-evaluation, infix-expression-parser, infix-notation, parsing, parsing-library, python, python-3, python3, python3-library, safe-evaluation
- Language: Python
- Size: 304 KB
- Stars: 10
- Watchers: 4
- Forks: 5
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- Changelog: CHANGES
- License: LICENSE
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README
# plusminus
The **plusminus** package provides a ready-to-run arithmetic parser and evaluator,
based on [`pyparsing`](https://pyparsing-docs.readthedocs.io/en/latest/index.html)'s
[`infix_notation`](https://pyparsing-docs.readthedocs.io/en/latest/pyparsing.html#pyparsing.infixNotation)
helper method.
Strings containing 6-function arithmetic expressions can be parsed and evaluated using the
[`ArithmeticParser`](https://github.com/pyparsing/plusminus/blob/master/doc/arithmetic_parser.md#the-core-basicarithmeticparser):
```python
from plusminus import BaseArithmeticParser
parser = BaseArithmeticParser()
print(parser.evaluate("2+3/10"))
```
The parser can also return an Abstract Syntax Tree of `ArithNode` objects:
```python
parsed_elements = parser.parse("2+3/10")
```
Arithmetic expressions are evaluated following standard rules for operator precedence, allowing for use of parentheses to override:
()
|x|
∩ & ∪ | - ^ ∆ (set operations)
**
-
* / // × ÷ mod
+ -
< > <= >= == != ≠ ≤ ≥
in ∈ ∉ (element in/not in set)
not
and ∧
or ∨
? : (ternary)
Functions can be called:
abs ceil max
round floor str
trunc min bool
The `BaseArithmeticParser` also supports assignment of variables:
r = 5
area = π × r²
This last expression could be assigned using `@=` formula assignment:
area @= π × r²
As `r` is updated, evaluating `area` will be reevaluated using the new value.
An `ArithmeticParser` class is also defined, with more extensive operators,
including:
! - factorial
° - degree-radian conversion
√ ⁿ√ - square root and n'th root (2-9)
⁻¹ ⁰ ¹ ² ³ - common exponents as superscripts
and additional pre-defined functions:
sin asin rad gcd
cos acos deg lcm
tan atan ln rnd
sgn sinh log randint
gamma cosh log2
hypot tanh log10
This parser class can be used in applications using algebra or trigonometry
expressions.
Custom expressions can be defined using a simple
[`API`](https://github.com/pyparsing/plusminus/blob/master/doc/developer_api.md).
Example parsers are included for other specialized applications
and domains:
- dice rolling (`"3d6 + d20"`)
- time delta expressions (`"today() + 2d + 12h"`)
- retail and business expressions (`"20% off of 19.99"`)
- combinatoric expressions (`"6C2"` or `"5P3"` )
These parsers can be incorporated into other
applications to support the safe evaluation of user-defined domain-specific
expressions.