package_name_to_import_with.simplify module

Evaluate simplification expressions.

class Parentheses(value)

Bases: str, enum.Enum

Define supported brackets.

LEFT = '('

RIGHT = ')'

clean_and_tokenise_expression(raw_expression)

Extract tokens from arithmetic expression after pre-processing.

Parameters:

raw_expression (str) -- infix expression

Returns:

tokens in standard arithmetic expression

Return type:

collections.abc.Iterator[re.Match[str]]

Raises:

ValueError -- if unsupported characters are passed

convert_infix_expression(infix_expression_tokens)

Convert standard arithmetic expression into reverse Polish notation.

This implements shunting yard algorithm following pseudocode section in Wikipedia.

Parameters:

infix_expression_tokens (collections.abc.Iterator[re.Match[str]]) -- tokens in standard arithmetic expression

Returns:

postfix arithmetic expression

Return type:

list[BinaryArithmeticOperator | float]

Raises:

ValueError -- if brackets are not matching

Notes

1. Initiate operator stack and output queue.

2. Modify based on token type.

   • Number

     1. Convert to number (using float).

     2. Add to output_queue.

   • Operator

     1. Convert to operator (using BinaryArithmeticOperator).

     2. Move top lower precedence operators from operator_stack into output_queue.

     3. Add to operator_stack.

   • Left Parenthesis

     1. Convert to bracket (using Parentheses).

   • Right Parenthesis

     1. Convert to bracket (using Parentheses).

     2. Move operators from operator_stack into output_queue till left bracket.

     3. Discard left bracket from top of operator_stack.

References

Wikipedia.

evaluate_postfix_expression(postfix_expression)

Evaluate postfix arithmetic expression in reverse Polish notation.

Parameters:

postfix_expression (list[BinaryArithmeticOperator | float]) -- elements of arithmetic expression in postfix format

Returns:

result of arithmetic expression

Return type:

float

solve_simplification(expression)

Evaluate arithmetic expression.

Parameters:

expression (str) -- standard arithmetic expression

Returns:

result of arithmetic expression

Return type:

float

Examples

>>> from package_name_to_import_with import solve_simplification
>>> solve_simplification("0 + 1 - 2 * 3 / 4")
-0.5
>>> solve_simplification("5 * 6 / (7 + 8) - 9")
-7.0