Search a list for a duplicate in Python

Question

newWord = print(input('Enter a word: '))
myList = ["apple", "mango"]

def ifWordAlreadyExists(str):
    for x in myList:
        if x == str:
            index = index(x)
            query = print(input('Word ', x ,'is already in index ', index , 'are you sure you want to include it? '))
            if query == 'y':
                return str
            else:
                return 0
myList.append(ifWordAlreadyExists(newWord))
print(myList)

Output

Enter a word: apple
apple
['apple', 'mango', None]

Why is query not showing and newWord not appending to myList?
PS. I’m a beginner in Python so I would appreciate if someone could point put what I’m doing wrong :))

Asked By: user11520020

||

Source

Answer 1

Basically print() returns None and you don’t need to place input() method in print() because input() can also print something to the screen but accept an input.
You can change the code to:

myList = ["apple", "mango"]
newWord = input('Enter a word: ')
check = newWord in myList
if not check:
    myList.append(newWord)
else:
    print('Word', newWord ,'is already on the list are you sure you want to include it?', end=" ")
    query = input().lower().startswith('y')
    if query:
        myList.append(newWord)
print(myList)

Output

Enter a word: apple
Word apple is already on the list are you sure you want to include it? yes
['apple', 'mango', 'apple']

Answered By: Comsavvy

Answer 2

The print function does not return any values

If you want to print the entered value, you must use print on the bottom line.

newWord = input("Word:")
print(newWord) #like this
myList = ["apple", "mango"]

def ifWordAlreadyExists(str):
    for x in myList:
        if x == str:
            index = myList.index(x)
            query = input("Word {0} is already in index {1} are you sure you want to include it:".format(str,index))
            if query == 'y':
                return str
            else:
                return 0
myList.append(ifWordAlreadyExists(newWord))
print(myList)

Answered By: Salim Baskoy

Answer 3

newWord is None if you use newWord = print(input('Enter a word: ')), it should be newWord = input('Enter a word: '). Besides, you don’t have to use a for loop inside the function, the method index of a python list can solve it directly, for example

newWord = input('Enter a word: ')
myList = ["apple", "mango"]

def ifWordAlreadyExists(to_check):

    try:
        idx = myList.index(to_check)
        query = input('%s is already in the list, are you sure you want to include it? ' % to_check)
        if query == 'y': return to_check
        return 0
    except ValueError:
        return to_check
    
myList.append(ifWordAlreadyExists(newWord))
print(myList)

Answered By: meTchaikovsky

Answer 4

You can use the count() to find duplicates in a list.

def check_duplicates(lst: list):
    for item in lst:
        
        if lst.count(item) > 1:
            return item
        else:
            return "No Duplicates!"

Answered By: Lawrence Dotse

Search a list for a duplicate in Python

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