# Shuting-yard algorithm
This repo is a Python (>= 3.9) module containing an implementation of the [Shunting-yard algorithm](https://en.wikipedia.org/wiki/Shunting_yard_algorithm), which converts any "regular" mathematical expression into its [Reverse Polish Notation](https://en.wikipedia.org/wiki/Reverse_Polish_notation) equivalent, and then can evaluate it.
# Installation
This module is available [on Pypi](https://pypi.org/project/shunting-yard/). To install it, just run :
```bash
pip install shunting-yard --user
```
Or alternatively you can use :
```bash
git clone https://github.com/charon25/ShuntingYard.git
cd ShuntingYard
python setup.py install --user
```
You can check the installation was successful by running the following command and getting `1 = 1` as output :
```bash
python -m shunting_yard 1
```
# Usage
Either use it directly in a command line interface with :
```bash
python -m shunting_yard <expression>
```
For instance :
```bash
>>> python -m shunting_yard "1 + cos(pi)"
1 + cos(pi) = 0.0
```
Or you can use it in a Python script with :
```python
import shunting_yard as sy
print(sy.compute("2^32 - sqrt(tan(42))"))
```
## Allowed functions
By default, the module can process the 5 basic operations (`+`, `-`, `*`, `/`, `^`) as well as those functions :
- sqrt
- sin, cos, tan
- min, max (with 2, 3 or 4 arguments)
- abs
As well as the constants `pi` and `e`.
These operations and functions can be mixed however you want.
Furthermore, you can add more functions with the optional parameters `additional_functions` of the `sy.compute` function. It should be a dictionary whose keys are string, and values are a tuple containing first the number of expected argument to the function, and then the function itself. For example :
```python
import math
additional_functions = {
'gamma': (0, lambda:0.5772156649015329), # create new constant
'inc': (1, lambda x:x + 1), # using lambda
'exp': (1, math.exp), # using already existing function
'gcd3': (3, math.gcd) # 3 parameters
}
```
The `sy.compute` (and `sy.shuting_yard`) also have extra parameters :
- `case_sensitive` (bool, defaults to `True`) : if `True`, will consider `sin` and `SIN` different functions.
- `variable` (str, optional) : if defined, will consider any token matching it as a number. This is useful in expression such as `min(x, 1)` to get `x` to behave as a number.
## Additional features
### Implicit multiplication
This program supports implicit multiplication (when the `*` symbol is omitted). They can have multiple forms, such as :
- `(1+2)(2+3)`
- `2sin(pi)`
- `(1+2)3`
- `sin(pi)10`
### Functions
Instead of just calling the `sy.compute` function, you can break it into its parts :
- `sy.shunting_yard` will return the RPN equivalent expression of the given mathematical expression ;
- `sy.compute_rpn` will use this expression and compute its value (use the `additional_functions` parameters here).
Furthermore, you can just use the `sy.tokenize` function to transform a mathematical expression into its base components (returns a generator).
Examples :
```python
import shunting_yard as sy
print(sy.shunting_yard('2 * sin(5/2)'))
# 2 5 2 / sin *
print(sy.compute_rpn('pi 2 / sin'))
# 1.0
print(sy.compute_rpn('3 inc', {'inc': (1, lambda x:x + 1)}))
# 4
print(list(sy.tokenize('1+(2 * 3) - 4 * (2 / 3)')))
# ['1', '+', '(', '2', '*', '3', ')', '-', '4', '*', '(', '2', '/', '3', ')']
```
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"description": "# Shuting-yard algorithm\r\n\r\nThis repo is a Python (>= 3.9) module containing an implementation of the [Shunting-yard algorithm](https://en.wikipedia.org/wiki/Shunting_yard_algorithm), which converts any \"regular\" mathematical expression into its [Reverse Polish Notation](https://en.wikipedia.org/wiki/Reverse_Polish_notation) equivalent, and then can evaluate it.\r\n\r\n# Installation\r\n\r\nThis module is available [on Pypi](https://pypi.org/project/shunting-yard/). To install it, just run :\r\n\r\n```bash\r\npip install shunting-yard --user\r\n```\r\n\r\nOr alternatively you can use :\r\n\r\n```bash\r\ngit clone https://github.com/charon25/ShuntingYard.git\r\ncd ShuntingYard\r\npython setup.py install --user\r\n```\r\n\r\nYou can check the installation was successful by running the following command and getting `1 = 1` as output :\r\n\r\n```bash\r\npython -m shunting_yard 1\r\n```\r\n\r\n\r\n# Usage\r\n\r\nEither use it directly in a command line interface with :\r\n\r\n```bash\r\npython -m shunting_yard <expression>\r\n```\r\n\r\nFor instance :\r\n\r\n```bash\r\n>>> python -m shunting_yard \"1 + cos(pi)\"\r\n\r\n1 + cos(pi) = 0.0\r\n```\r\n\r\nOr you can use it in a Python script with :\r\n\r\n```python\r\nimport shunting_yard as sy\r\n\r\nprint(sy.compute(\"2^32 - sqrt(tan(42))\"))\r\n```\r\n\r\n## Allowed functions\r\n\r\nBy default, the module can process the 5 basic operations (`+`, `-`, `*`, `/`, `^`) as well as those functions :\r\n - sqrt\r\n - sin, cos, tan\r\n - min, max (with 2, 3 or 4 arguments)\r\n - abs\r\n\r\nAs well as the constants `pi` and `e`.\r\n\r\nThese operations and functions can be mixed however you want.\r\n\r\nFurthermore, you can add more functions with the optional parameters `additional_functions` of the `sy.compute` function. It should be a dictionary whose keys are string, and values are a tuple containing first the number of expected argument to the function, and then the function itself. For example :\r\n\r\n```python\r\nimport math\r\n\r\nadditional_functions = {\r\n 'gamma': (0, lambda:0.5772156649015329), # create new constant\r\n 'inc': (1, lambda x:x + 1), # using lambda\r\n 'exp': (1, math.exp), # using already existing function\r\n 'gcd3': (3, math.gcd) # 3 parameters\r\n}\r\n```\r\n\r\nThe `sy.compute` (and `sy.shuting_yard`) also have extra parameters :\r\n - `case_sensitive` (bool, defaults to `True`) : if `True`, will consider `sin` and `SIN` different functions.\r\n - `variable` (str, optional) : if defined, will consider any token matching it as a number. This is useful in expression such as `min(x, 1)` to get `x` to behave as a number.\r\n\r\n## Additional features\r\n\r\n### Implicit multiplication\r\n\r\nThis program supports implicit multiplication (when the `*` symbol is omitted). They can have multiple forms, such as :\r\n- `(1+2)(2+3)`\r\n- `2sin(pi)`\r\n- `(1+2)3`\r\n- `sin(pi)10`\r\n\r\n### Functions\r\n\r\nInstead of just calling the `sy.compute` function, you can break it into its parts :\r\n - `sy.shunting_yard` will return the RPN equivalent expression of the given mathematical expression ;\r\n - `sy.compute_rpn` will use this expression and compute its value (use the `additional_functions` parameters here).\r\n\r\nFurthermore, you can just use the `sy.tokenize` function to transform a mathematical expression into its base components (returns a generator).\r\n\r\nExamples :\r\n\r\n```python\r\nimport shunting_yard as sy\r\n\r\nprint(sy.shunting_yard('2 * sin(5/2)'))\r\n# 2 5 2 / sin *\r\n\r\nprint(sy.compute_rpn('pi 2 / sin'))\r\n# 1.0\r\n\r\nprint(sy.compute_rpn('3 inc', {'inc': (1, lambda x:x + 1)}))\r\n# 4\r\n\r\nprint(list(sy.tokenize('1+(2 * 3) - 4 * (2 / 3)')))\r\n# ['1', '+', '(', '2', '*', '3', ')', '-', '4', '*', '(', '2', '/', '3', ')']\r\n\r\n```\r\n",
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