List comprehensions Conversion

Question

i started learning Python recently and i am facing difficulty converting the below piece of code into a list comprehension:

    list = []     #An empty List
    for key,value in defaultDict.items():#iterate through the default dict
        for i in defaultDict[key]:#iterate through the list in the defaultDict
            if i not in list:#If the item in the list is not present in the main list
                list.append(i)#append it

Is it possible for me to even do it??Any help with this is much appreciated.

@self: OP will need an inner loop. It seems that `value` is itself a list — inspectorG4dget, Oct 03 '16 at 01:56
`value` is a list, sure, but he should use `value` instead of a key lookup — Ryan, Oct 03 '16 at 01:56
That is absolutely true. That second loop should be `for i in value` — inspectorG4dget, Oct 03 '16 at 01:57
@self :Yes, i should have!!I realized it after reading your comment!!I am very new to python, so it dint flash that i could do it!!Thanks a lot for the comment though!!Now i know two better ways to meet my goals!!Lol!! — N_B, Oct 03 '16 at 02:11

score 4 · Accepted Answer · edited May 23 '17 at 12:00

4

Very straightforward: use a nested list comprehension to get all is and a set to remove duplicates.

list(set([item for __, value in defaultDict.items() for item in value]))

Let's break it down:

[item for key,value in defaultDict.items() for item in value] is a nested list comprehension.
set(...) will remove all duplicates - the equivalent of if i not in list: list.append(i) logic you have
list(set(...)) will convert the set back to a list for you.

edited May 23 '17 at 12:00

Community

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answered Oct 03 '16 at 01:56

Akshat Mahajan

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Wow!!This solution is so compact and nice!!Awesome man!!Thanks for breaking it up!!So perfect – N_B Oct 03 '16 at 02:04
Glad to help :) – Akshat Mahajan Oct 03 '16 at 02:05
Sure!!I couldn't accept it due to the time restriction. I will go ahead and do it right away!! – N_B Oct 03 '16 at 02:08

List comprehensions Conversion

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