yuanhang2008 / mep

Mathematical Expression Parsing

MEP

Mathematical Expression Parsing.

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install

Run auto_install_1.bat to install MEP, if it doesn't work, try enter pip install setuptools and pip install wheel to install the two necessary libraries, please. auto_install_2.bat can install MEP as a temporary modules, you can use it if you are just here to test the library or try some features, not at work or important occasions.

usage

formula

Use MEP.Formula and MEP.X to product a formula.

>>>import MEP
>>>f = MEP.Formula(2 * MEP.X - 1)

Formula objects are printable and __str__ method is defined, but text method is recommended.

>>>print(f)
<Formula f(x)=2*x-1>
>>>str(f)
'<Formula f(x)=2*x-1>'
>>>f.text()
'2*x-1'

symbol

A Symbol object can be defined by users, a symbol's name must be a letter.

A = MEP.Symbol('a')
f = Formula(A * 2)

A formula can contain multiple symbols, and 'x', 'y', 'z' are built-in, they are default symbols in MEP.

Use variable symbols to get all defined symbols's sign, you can also visit sign to get the sign of a symbol.

>>>MEP.symbols
{'x', 'y', 'z', 'a'}

>>>A.sign
'a'

draw

Draw is used to draw a function plot in matplotlib.

>>>range_ = (-100, 100)

>>>f1 = Formula(2 * MEP.X + 1)
>>>f2 = Formula(MEP.X ** 2)

>>>f1.draw(range_)
>>>f2.draw(range_)

>>>Draw.display()

More functions, such as clear: clear all the formulas in Draw object.

>>>Draw.clear()
>>>Draw.display()
# Nothing to show

setprec: set the precision of the plot. the larger the precision, the more detailed the plot, but the slower the program runs.

However, drawing a formula contains multiple symbols is invalid.

expression

Substitute a value to build a new expression.The substituted values should correspond to the symbols by using keyword arguments, the key names are symbols's signs.

>>>f = MEP.Formula(2 * MEP.X - 1)
>>>exp = f.subs(x=2) # an Expression object
>>>exp.value()
3

>>>print(exp)
<Expression f(x=2)=2*2-1>
>>>exp.text()
'2*2-1'

math

Class Math provides with some special functions, which can participate in formula generations.

>>>f = Formula(Math.abs(9 - MEP.X)) # equal to |9-x|
>>>exp = f.subs(x=12)
>>>exp.value()
3

curry

curry method can curry a formula and return the curried formula.

>>>f1 = MEP.Formula(X + Y)
>>>f2 = f1.curry(x=2)
>>>exp = f2.subs(y=3)

>>>exp.value
5

Features in Development

• merge formulas by functions in Math
• show functions images with tkinter
• code for test (too lazy to write
• analyze formulas, such as calculating definition domains
• document strings
• optimize the code
  ...

Bugs/Requests

Please send bug reports and feature requests through github issue tracker.

About Author

Bilbili: l_yuanhang_l Github: yuanhang2008 QQ: 远航

License

Copyright yuanhang2008, 2023.

Distributed under the terms of the MIT License.

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