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    <p>A <code>list</code> keeps order, <code>dict</code> and <code>set</code> don't: when you care about order, therefore, you must use <code>list</code> (if your choice of containers is limited to these three, of course;-).</p> <p><code>dict</code> associates with each key a value, while <code>list</code> and <code>set</code> just contain values: very different use cases, obviously.</p> <p><code>set</code> requires items to be hashable, <code>list</code> doesn't: if you have non-hashable items, therefore, you cannot use <code>set</code> and must instead use <code>list</code>.</p> <p><code>set</code> forbids duplicates, <code>list</code> does not: also a crucial distinction. (A "multiset", which maps duplicates into a different count for items present more than once, can be found in <code>collections.Counter</code> -- you could build one as a <code>dict</code>, if for some weird reason you couldn't import <code>collections</code>, or, in pre-2.7 Python as a <code>collections.defaultdict(int)</code>, using the items as keys and the associated value as the count).</p> <p>Checking for membership of a value in a <code>set</code> (or <code>dict</code>, for keys) is blazingly fast (taking about a constant, short time), while in a list it takes time proportional to the list's length in the average and worst cases. So, if you have hashable items, don't care either way about order or duplicates, and want speedy membership checking, <code>set</code> is better than <code>list</code>.</p>
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    1. POIn Python, when to use a Dictionary, List or Set?
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    1. USAlex Martelli
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    1. COI wish I could donate my answer votes to yours... Hey everyone, this is where the meat is :)
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    2. COI took the bait! thanks for the summary!
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    3. CO@Jon, thanks! Hmmm, maybe the idea of "transferring upvotes" (at some "discount rate", e.g., 2 for 1) is worth discussing in meta...?-) I know I've felt similarly on certain occasions...
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Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

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