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POComparing lists of lists and writing certain elements into a new list
 

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  1. POComparing lists of lists and writing certain elements into a new list
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    <p>It looks like this question has been asked dozens of times, but none of the answers have helped me out, so I'm afraid I'm asking it again (please don't hate me!). I have two lists of lists: </p> <pre><code>amm = [['0005FC66DF', '4403'", ',\n'], [" ['0001C52E02', '4406'", ',\n'],etc] </code></pre> <p>and</p> <pre><code>data = [['07/11/2012', '09:53:36', 'Thing', '#0F', '0006E7895B', 'T', 'U\n'], ['05/13/2012', '09:54:27', 'Thing', '#0F', '0006E3DADA', 'T', 'U\n'], etc]. </code></pre> <p>I want to see if the 5th element in a list in data is the same as the first element in a list in amm, and if so, I want to write the list from data to a new list of lists, amv. I have tried EVERYTHING. I started with</p> <pre><code>for i in data: if data[i][4] in amm: amv[i].append(i) </code></pre> <p>which didn't write anything to amv, so I tried</p> <pre><code>amv=[item for item in data if item[4] in[items for items in amm]] </code></pre> <p>which had the same problem, so I tried</p> <pre><code> for i in data: for j in amm: if i[4] == j[0]: amv.append(j) </code></pre> <p>and a million (probably slightly more accurate) variations on these themes. This should be such a simple thing to do but it's just not working for me. Any help would be very, very much appreciated. Thanks in advance!</p> <p>EDIT Sorry this wasn't very clear. What I'm trying to do is write a new list (amv) that contains all the lists in data that have their fifth element appear in amm. All of the scripts I've shown haven't added anything to the new list, amv. amv has always stayed empty, and I can't figure out why..</p>
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    1. USSnaaa
    1. USSnaaa
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    1. COAre these elements you're looking for (`"0005FC66DF"`) unique across both `data` and `amm`?
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      1. USTim Pietzcker
    2. COYour question neither explains what exactly you are trying to do, nor how your approaches fail. What's wrong with the e.g. the last code snippet (except that it is very inefficient)?
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      1. USSven Marnach
    3. COThey'll be repeated somewhere between 1 and few hundred times in data, but they should be unique in amm. About half of the ones in data will be in amm
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      1. USSnaaa
 

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