NLTK Tokenize: Find parenthesized expressions in a given string and divides into a sequence of substrings

Last update on May 28 2022 13:00:10 (UTC/GMT +8 hours)

NLTK Tokenize: Exercise-9 with Solution

Write a Python NLTK program to find parenthesized expressions in a given string and divides the string into a sequence of substrings.

Sample Solution:

Python Code:

from nltk.tokenize import SExprTokenizer
text = '(a b (c d)) e f (g)'
print("\nOriginal Tweet:")
print(text)
print(SExprTokenizer().tokenize(text))
text = '(a b) (c d) e (f g)'
print("\nOriginal Tweet:")
print(text)
print(SExprTokenizer().tokenize(text))
text = '[(a b (c d)) e f (g)]'
print("\nOriginal Tweet:")
print(text)
print(SExprTokenizer().tokenize(text))
print(text)
print(SExprTokenizer().tokenize(text))
text = '{a b {c d}} e f {g}'
print("\nOriginal Tweet:")
print(text)
print(SExprTokenizer().tokenize(text))

Sample Output:

Original Tweet:
(a b (c d)) e f (g)
['(a b (c d))', 'e', 'f', '(g)']

Original Tweet:
(a b) (c d) e (f g)
['(a b)', '(c d)', 'e', '(f g)']

Original Tweet:
[(a b (c d)) e f (g)]
['[', '(a b (c d))', 'e', 'f', '(g)', ']']
[(a b (c d)) e f (g)]
['[', '(a b (c d))', 'e', 'f', '(g)', ']']

Original Tweet:
{a b {c d}} e f {g}
['{a b {c d}} e f {g}']

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Previous: Write a Python NLTK program that will read a given text through each line and look for sentences. Print each sentence and divide two sentences with “==============”.

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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