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Python Math: Parse math formulas and put parentheses around multiplication and division

Python Math: Exercise-60 with Solution

Write a Python program to parse math formulas and put parentheses around multiplication and division.

Sample Solution:-

Python Code:

#https://gist.github.com/ohaz/ed0b14a487b0569aad2d
import ast

def recurse(node):
    if isinstance(node, ast.BinOp):
        if isinstance(node.op, ast.Mult) or isinstance(node.op, ast.Div):
            print('(', end='')
        recurse(node.left)
        recurse(node.op)
        recurse(node.right)
        if isinstance(node.op, ast.Mult) or isinstance(node.op, ast.Div):
            print(')', end='')
    elif isinstance(node, ast.Add):
        print('+', end='')
    elif isinstance(node, ast.Sub):
        print('-', end='')
    elif isinstance(node, ast.Mult):
        print('*', end='')
    elif isinstance(node, ast.Div):
        print('/', end='')
    elif isinstance(node, ast.Num):
        print(node.n, end='')
    else:
        for child in ast.iter_child_nodes(node):
            recurse(child)


def search_expr(node):
    returns = []
    for child in ast.iter_child_nodes(node):
        if isinstance(child, ast.Expr):
            return child
        returns.append(search_expr(child))
    for ret in returns:
        if isinstance(ret, ast.Expr):
            return ret
    return None


formula = '4+5*7/2'

a = ast.parse(formula)

expr = search_expr(a)
if expr is not None:
    recurse(expr)
print()

Sample Output:

4+((5*7)/2)

Flowchart:

Flowchart: Parse math formulas and put parentheses around multiplication and division

Python Code Editor:

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Python: Tips of the Day

Getting rid of unwanted characters:

You can get rid of whitespaces or any specific character using strip methods in Python. You can use either plain strip for both sides, lstrip for the left side and rstrip for the right side only.

str="+++Welcome python+++"
str.strip()

print(str)

Output:

+++Welcome python+++