Expand a inner list into a flat list

Question

I have a list of list (var_list) that I want to "expand" into a flat list (list1), see bellow:

environment = {
    "KEY1": "VALUE1",
    "KEY2": "VALUE2",
}

var_list = [
    ["var", f"{key}={value}"] for key, value in environment.items()
]

list1 = ["foo", "bar"]

result = list1.extend(var_list)

# PS. Must be a list, not a `' '.join`

print(f"{result=}") # None.

print(result == ["foo", "bar", "var", "KEY1=KEY1", "var", "KEY2=KEY2"]) # returns False. Should be True or equal

How can I do this in python, without using ' '.join?

@Skhaz: you must admit that `result = list1.extend(...` is *part* of the problem. — quamrana, Apr 20 '21 at 13:50

score 0 · Accepted Answer · answered Apr 20 '21 at 13:50

0

Found the solution, I can use operator.concat

list1 = ["foo", "bar"] + functools.reduce(operator.concat, var_list)

answered Apr 20 '21 at 13:50

Rodrigo

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Surely now `print(f"{result=}") ` will fail. – quamrana Apr 20 '21 at 13:53
There's an error is line `result = list1.extend(var_list)`, because the extend method changes the `list1` itself and returns None. So, you don't need a `result` list. – wensiso Apr 20 '21 at 14:03

Expand a inner list into a flat list

1 Answers1