Pyparsing Nested Expression: Return Nest Characters in ParseResults

Question

I'm currently using pyparsing to identify whether a nested parenthesis is being used in a string, in order to identify reference numbers being mistakenly concatenated to words.

For instance, 'apple(4)'.

I want to be able to identify the reference subtoken ('(4)'). However, when I use searchString, it returns a ParseResults object of [[7]], which doesn't provide the parenthesis. I want to find the substring in the original token, so I need to have the nest characters included in the ParseResults object. Ie, I want to search for '(4)'. Is there a way to make searchString return the nest characters.

Can you be more specific about just what those parenthetical expressions might look like, that you need to support nesting? nestedExpr is a quick-and-dirty helper to quickly jump over nested parens, braces, brackets, etc., preserving the structure from the nesting. If you just want the raw substring, wrap nestedExpr in originalTextFor, which should include the enclosing ()'s. But if you really want to make sense of the contents, then I'd suggest you define actual recursive expressions for them. — PaulMcG
– PaulMcG, Commented Jun 14, 2017 at 21:05

stovfl · Accepted Answer · 2017-06-15 12:47:56Z

1

Question: Is there a way to make searchString return the nest characters.

Consider the following Examples:

data = 'apple(4), banana(13), juice(1)'

from pyparsing import Word, nums, alphas

nested = Word(alphas) + '(' + Word(nums) + ')'
for item in data.split((',')):
    print(item, "->", nested.searchString(item))

Output:

apple(4), ->[['apple', '(', '4', ')']]
 banana(13), ->[['banana', '(', '13', ')']]
 juice(1), ->[['juice', '(', '1', ')']]

import re

nObj = re.compile('(\w+?)(\(\d+\))')
findall = nObj.findall(data)
print('findall:{}'.format(findall))

Output:

findall:[('apple', '(4)'), ('banana', '(13)'), ('juice', '(1)')]

Tested with Python: 3.4.2

answered Jun 15, 2017 at 12:47

stovfl

15.6k7 gold badges26 silver badges54 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

PaulMcG Over a year ago

This answer doesn't support nesting, but it is not clear from the OP's example that nesting is actually required. What you have here should work fine with the original sample text. Two other things you might try - add a parse action to auto-convert the Word(nums) to an int; and add results names to the "apple" and the "4" quantity to make access to them easier in the parsed results.

stovfl Over a year ago

@Paul: I interpreted the OP nest characters with (...). Awaiting the OP comment ...

Collectives™ on Stack Overflow

Pyparsing Nested Expression: Return Nest Characters in ParseResults

1 Answer 1

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related