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POComparing massive lists of dictionaries in python
 

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    <p>I never actually thought I'd run into speed-issues with python, but I have. I'm trying to compare really big lists of dictionaries to each other based on the dictionary values. I compare two lists, with the first like so</p> <pre><code>biglist1=[{'transaction':'somevalue', 'id':'somevalue', 'date':'somevalue' ...}, {'transactio':'somevalue', 'id':'somevalue', 'date':'somevalue' ...}, ...] </code></pre> <p>With 'somevalue' standing for a user-generated string, int or decimal. Now, the second list is pretty similar, except the id-values are always empty, as they have not been assigned yet.</p> <pre><code>biglist2=[{'transaction':'somevalue', 'id':'', 'date':'somevalue' ...}, {'transactio':'somevalue', 'id':'', 'date':'somevalue' ...}, ...] </code></pre> <p>So I want to get a list of the dictionaries in biglist2 that match the dictionaries in biglist1 for all other keys <em>except</em> id.</p> <p>I've been doing </p> <pre><code>for item in biglist2: for transaction in biglist1: if item['transaction'] == transaction['transaction']: list_transactionnamematches.append(transaction) for item in biglist2: for transaction in list_transactionnamematches: if item['date'] == transaction['date']: list_transactionnamematches.append(transaction) </code></pre> <p>... and so on, not comparing id values, until I get a final list of matches. Since the lists can be really big (around 3000+ items each), this takes quite some time for python to loop through.</p> <p>I'm guessing this isn't really how this kind of comparison should be done. Any ideas?</p>
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