在文件中搜索回文，并使用python将其打印在列表中

Question

Im trying to write a code that reads a file and then returns a list of all the palindromes in the file. So I've created a function checks if a word is a palindrome and I've tried to write another function that reads the file, gets rid of the blank space, splits into words, and then tests each word to see if it is a palindrome. If it is a palindrome, then I add it into the list that I will print in the end. However, I am getting an error "AttributeError: 'tuple' object has no attribute 'append'" How can I get the palindromes added into this list?

def findPalindrome(filename):
    #an empty list to put palindromes into
    list3 = ()
    #open the file 
    for line in open(filename):
        #strip the lines of blank space
        list1 = line.strip()
        #Split the lines into words
        list2 = line.split()
        #call one of the words
        for x in list2:
            #test if it is a palindrome
            if isPalindrome(x):
                #add to list3
                list3.append(x)
    #return the list of palindromes
    return list3

Answer 1

The problem here is that list3 isn't actually a list. Instead of doing list3 = () , do list3 = [] .

Doing () will create a tuple , which is a type of data structure similar to a list, but cannot be altered after they're first created. This is why you're unable to append to it, since that would alter the tuple. The [] creates an actual list, which is mutable and can be altered over time.

Answer 2

Remove:

list3=() # because it creates an empty tuple

by:

list3=list() # create an empty list

Also replace :

list2 = line.split()

by:

list2 = list1.split() # because stripped line is in list1 not in line