Error when running palindrome finder code: [TypeError: 'builtin_function_or_method' object is not subscriptable]

Question

palindrome | ˈpalənˌdrōm | noun a word, phrase, or sequence that reads the same backward as forward, e.g., madam or nurses run.

The 'palindrome_finder' project includes 3 files: a dictionary file named 'dict.txt', a dictionary loader file named 'load_dictionary.py', as well as the main file (that recognizes palindromes within the dictionary file) named 'palingram_finder.py'.

As soon as I run the file, I receive the following error:

Traceback (most recent call last):
  File "/Users/cheshirecat/Desktop/python_projects/palingram_finder/palingram_finder.py", line 16, in <module>
    if word[::-1] == word and len(word) >= 3:
       ~~~~^^^^^^
TypeError: 'builtin_function_or_method' object is not subscriptable
[Finished in 58ms with exit code 1]

For context, here are the two python files.

load_dictionary

import sys

def load(file):
    """Open a text file and return a list of lowercase strings"""

    try:
        with open(file) as in_file:
            loaded_txt = in_file.read().strip().split()
            loaded_txt = [x.lower for x in loaded_txt]

            return loaded_txt

    except IOError as e:
        print("{}\n Error opening {}. Terminating program.".format(e, file), file=sys.stderr)
        sys.exit(1)

palingram_finder

from load_dictionary import load
from pprint import pp

word_list = load('./dict.txt')
palindrome_list = []

for word in word_list:
    if word[::-1] == word and len(word) >= 3:
        palindrom_list.append(word)

print("Number of palindromes found: {}\n\n".format(len(palindrome_list)))
pp(palindrome_list)

Attempts at a fix: I tested a simplified version of the palindrome recognition code using the built in python shell as shown below.

>>> word_list = ['betrayal', 'enigma', 'tenet', 'multitude', 'did']
>>> 
>>> palindrome_list = []
>>> 
>>> for word in word_list:
...     if len(word) >= 3 and word[::-1] == word:
...             palindrome_list.append(word)
... 
>>> palindrome_list
['tenet', 'did']
>>> exit()

Since it worked, I decided that the problem was with the way the dictionary was being loaded. This is where I get stuck, for when I load the dictionary within Sublime text editor's shell in the same manner as load_dictionary.py, I am given a list of strings. Shouldn't it work, then?

Answer 1

The error you're getting is due to this line in load_dictionary.py file:

loaded_txt = [x.lower for x in loaded_txt]

You are not calling x.lower, just referencing it. Call it as a method:

loaded_txt = [x.lower() for x in loaded_txt]

This will solve your issue 😊.