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:
Python Code Editor:
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Python: Tips of the Day
Find current directory and file's directory:
To get the full path to the directory a Python file is contained in, write this in that file:
import os dir_path = os.path.dirname(os.path.realpath(__file__))
(Note that the incantation above won't work if you've already used os.chdir() to change your current working directory, since the value of the __file__ constant is relative to the current working directory and is not changed by an os.chdir() call.)
To get the current working directory use
import os cwd = os.getcwd()
Documentation references for the modules, constants and functions used above:
- The os and os.path modules.
- The __file__ constant
- os.path.realpath(path) (returns "the canonical path of the specified filename, eliminating any symbolic links encountered in the path")
- os.path.dirname(path) (returns "the directory name of pathname path")
- os.getcwd() (returns "a string representing the current working directory")
- os.chdir(path) ("change the current working directory to path")
Ref: https://bit.ly/3fy0R6m
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