python - How to replace words in a string using a dictionary mapping

Question

I have the following sentence

a = "you don't need a dog"

and a dictionary

dict =  {"don't": "do not" }

But I can't use the dictionary to map words in the sentence using the below code:

''.join(str(dict.get(word, word)) for word in a)

Output:

"you don't need a dog"

What am I doing wrong?

Answer 1

Here is one way.

a = "you don't need a dog"

d =  {"don't": "do not" }

res = ' '.join([d.get(i, i) for i in a.split()])

# 'you do not need a dog'

Explanation

• Never name a variable after a class, e.g. use d instead of dict.
• Use str.split to split by whitespace.
• There is no need to wrap str around values which are already strings.
• str.join works marginally better with a list comprehension versus a generator expression.