Adding a string to all keys in dictionary (Python)

Question

I'm new to Python and Pyspark and I'm practicing TF-IDF. I split all words from sentences in the txt file, removed punctuations, removed the words that are in the stop-words list, and saved them as a dictionary with the codes below.

x = text_file.flatmap(lambda line: str_clean(line).split()    
x = x.filter(lambda word: word not in stopwords    
x = x.reduceByKey(lambda a,b: a+b)    
x = x.collectAsMap()

I have 10 different txt files for this same process. And I'd like to add a string like "@d1" to keys in dictionary so that I can indicate that the key is from document 1.

How can I add "@1" to all keys in the dictionary?

Essentially my dictionary is in the form:

{'word1': 1, 'word2': 1, 'word3': 2, ....}

And I would like it to be:

{'word1@d1': 1, 'word2@d1': 1, 'word3@d1': 2, ...}

Answer 1

Try a dictionary comprehension:

{k+'@d1': v for k, v in d.items()}

In Python 3.6+, you can use f-strings:

{f'{k}@d1': v for k, v in d.items()}