Regex splitting with multiple end brackets-CodePudding

I have an input of 10 sqrt(10 (100*20) 20) sqrt(5) which I need to be able to split up into sqrt(...) as many times as sqrt appears (in this instance, twice). The problem I am having is trying to split this up, I have tried on my own and come up with this (sqrt\()(?<=sqrt\()(. ?)(\) ) but regex only registers the first ) it comes across whereas I need it to find the closing bracket.

As you can see in the picture the orange marker only covers up to the first bracket but i need it to end at the 20.

The desired output is a list as follows:

['10 ', 'sqrt(', '10 (100*20) 20', ')', ' ', 'sqrt(', '5', ')']

Thanks in advance

CodePudding user response：

Here is a solution using the ast module from the standard library. I'm assuming the expression is valid Python.

# Import parser from Python standard library
import ast

# I have an expression to process
expression = '10 sqrt(10 (100*20) 20) sqrt(5)'

# Parse it
tree = ast.parse(expression)

# Walk the parse tree
for node in ast.walk(tree):
    # Are we a function call?
    if isinstance(node, ast.Call):
        func = node.func
        # Are we a call to 'sqrt'?
        if expression[func.col_offset:func.end_col_offset] == 'sqrt':
            # We have what we want
            start = node.col_offset
            end = node.end_col_offset
            print(expression[start:end], start, end)

This outputs...

sqrt(5) 24 31
sqrt(10 (100*20) 20) 3 23

CodePudding user response：

You don't need to seperate the string. If you need to execute and return the result then, we can just use eval() to do it.


from math import *

query = "10 sqrt(10 (100*20) 20) sqrt(5)"

print(eval(query))

# Output: 57.29158928177503

But if you need to just split the equation, we can use classic split(). Reason: It's easier to manage if we don't know no. of sqrt() in equation.

s = "10 sqrt(10 (100*20) 20) sqrt(5)"

l = s.split('sqrt(')

d = [l[0]]

x = ''

for i in range(1, len(l)):

    if x: d.append(x)

    d.append('sqrt(')

    q = l[i]

    if i 1 == len(l): d.append(q)

    else:

        d.append(q[:-1])

        x = q[-1]



print(d)

# Output: ['10 ', 'sqrt(', '10 (100*20) 20)', ' ', 'sqrt(', '5)']

Peace!