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POAlternative data structure needed for deeply nested dictionary/map situation
 

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  1. POAlternative data structure needed for deeply nested dictionary/map situation
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    <p><strong>Some background of the data</strong>: some different games are being played, and each of them hosts a number of players. Each game consists of a number of rounds, and during each round each player involved makes an action. What I am trying to do here is to construct a data structure in memory for storing the complete history of individual actions taken by the players across all the games being played.</p> <p><strong>An obvious structure</strong> is a deeply nested dictionary/hashmap, where each <code>game_id</code> is mapped to a number of <code>player_id</code>s, and each player_id is mapped to different <code>round_number</code>s, and each <code>round_number</code> is mapped to an <code>action</code>. </p> <p>In other words, <code>game_id:player_id:round_number:action</code>. On the other hand, I can also use <code>game_id:round_number:player_id:action</code></p> <p><strong>Problem arises</strong> when I try to access the data structures above for different analytical purposes. For example, it's inconvenient to have <code>game_id:player_id:round_number:action</code>, if I want to know all the actions made by players in a particular round of a given game. Conversely, it is equally inconvenient to have <code>game_id:round_number:player_id:action</code>, if I want to know all the actions made by a particular player during the course of a given game. Unfortunately, in my case, I need to ask both those questions frequently.</p> <p>I wonder if there is <strong>a single data structure</strong> which can store such data and is convenient for accessing both player-level and round-level data as described above. The implementation will be in Python, if that matters.</p> <p><strong>EDIT</strong>: a few people have recommended in-memory sqlite database to handle such relational queries. However, its performance may be an issue for me, as discussed here: <a href="https://stackoverflow.com/questions/764710/sqlite-performance-benchmark-why-is-memory-so-slow-only-1-5x-as-fast-as-d">SQLite Performance Benchmark -- why is :memory: so slow...only 1.5X as fast as disk?</a> </p>
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    1. COSounds like you want a relational database which lives in memory. Maybe try looking into inMemory SQLite. http://www.sqlite.org/inmemorydb.html
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    2. CODo you only care about looking up via the two examples you give? Or do you want to do arbitrary lookups?
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    3. CO@DougT. Besides those two cases, I do also want to look up the specific action made by any given player at any given round of any given game.
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