How to use cosine similarity to compare 2 strings

text_similarity.py

from sklearn.feature_extraction.text import CountVectorizer
from sklearn.metrics.pairwise import cosine_similarity


corpus = [
    'This is my first sentence',
    'This is my second sentence'
]

vectorizer = CountVectorizer()
X = vectorizer.fit_transform(corpus)
print(cosine_similarity(X.toarray())[0][1]) # 0.8

corpus = [
    'This is the same sentence',
    'This is the same sentence'
]

vectorizer = CountVectorizer()
X = vectorizer.fit_transform(corpus)
print(cosine_similarity(X.toarray())[0][1]) # 1.0

corpus = [
    'Two sentences',
    'that are not the same at all'
]

vectorizer = CountVectorizer()
X = vectorizer.fit_transform(corpus)
print(cosine_similarity(X.toarray())[0][1]) # 0.0