Idiomatic Python to convert list to dict

[James Fassett]

Hi all,

Simple question really on a best practice. I want to avoid adding
duplicates to a list.

my_list = ['a', 'b', 'c', 'd', 'e']
dup_map = {}
for item in my_list:
    dup_map[item] = True

# ... sometime later

for complex_dict in large_list:
    if complex_dict["char"] not in dup_map:
        my_list.append(complex_dict["char"])
        dup_map[complex_dict["char"]] = True

For the first part (generating the duplicate map) is there a more
idiomatic Python method for flipping the list into a dict?

Is there a better way to achieve the overall objective (as hinted at
by the above algorithm)?

Thanks in advance for any tips.

James.