How to copy a dict and modify it in one line of code

Question

Very often I need to create dicts that differ one from another by an item or two. Here is what I usually do:

setup1 = {\'param1\': val1, 
            \'param         


        

Answer 1

If you just need to create a new dict with items from more than one dict, you can use:

dict(a.items() + b.items())

If both "a" and "b" have some same key, the result will have the value from b. If you're using Python 3, the concatenation won't work, but you can do the same by freezing the generators to lists, or by using the itertools.chain function.