How to return unique words from the text file using Python

Question

How do I return all the unique words from a text file using Python? For example:

I am not a robot

I am a human

Should return:

I

am

not

a

robot

human

Here is what I've done so far:

def unique_file(input_filename, output_filename):
    input_file = open(input_filename, 'r')
    file_contents = input_file.read()
    input_file.close()
    word_list = file_contents.split()

    file = open(output_filename, 'w')

    for word in word_list:
        if word not in word_list:
            file.write(str(word) + "\n")
    file.close()

The text file the Python creates has nothing in it. I'm not sure what I am doing wrong

Answer 1

for word in word_list:
    if word not in word_list:

every word is in word_list, by definition from the first line.

Instead of that logic, use a set:

unique_words = set(word_list)
for word in unique_words:
    file.write(str(word) + "\n")

sets only hold unique members, which is exactly what you're trying to achieve.

Note that order won't be preserved, but you didn't specify if that's a requirement.