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  • Storing simulation results in a persistent manner for Python?

    - by Az
    Background: I'm running multiple simuations on a set of data. For each session, I'm allocating projects to students. The difference between each session is that I'm randomising the order of the students such that all the students get a shot at being assigned a project they want. I was writing out some of the allocations in a spreadsheet (i.e. Excel) and it basically looked like this (tiny snapshot, actual table extends to a few thousand sessions, roughly 100 students). | | Session 1 | Session 2 | Session 3 | |----------|-----------|-----------|-----------| |Stu1 |Proj_AA |Proj_AB |Proj_AB | |----------|-----------|-----------|-----------| |Stu2 |Proj_AB |Proj_AA |Proj_AC | |----------|-----------|-----------|-----------| |Stu3 |Proj_AC |Proj_AC |Proj_AA | |----------|-----------|-----------|-----------| Now, the code that deals with the allocation currently stores a session in an object. The next time the allocation is run, the object is over-written. Thus what I'd really like to do is to store all the allocation results. This is important since I later need to derive from the data, information such as: which project Stu1 got assigned to the most or perhaps how popular Proj_AC was (how many times it was assigned / number of sessions). Question(s): What methods can I possibly use to basically store such session information persistently? Basically, each session output needs to add itself to the repository after ending and before beginning the next allocation cycle. One solution that was suggested by a friend was mapping these results to a relational database using SQLAlchemy. I kind of like the idea since this does give me an opportunity to delve into databases. Now the database structure I was recommended was: |----------|-----------|-----------| |Session |Student |Project | |----------|-----------|-----------| |1 |Stu1 |Proj_AA | |----------|-----------|-----------| |1 |Stu2 |Proj_AB | |----------|-----------|-----------| |1 |Stu3 |Proj_AC | |----------|-----------|-----------| |2 |Stu1 |Proj_AB | |----------|-----------|-----------| |2 |Stu2 |Proj_AA | |----------|-----------|-----------| |2 |Stu3 |Proj_AC | |----------|-----------|-----------| |3 |Stu1 |Proj_AB | |----------|-----------|-----------| |3 |Stu2 |Proj_AC | |----------|-----------|-----------| |3 |Stu3 |Proj_AA | |----------|-----------|-----------| Here, it was suggested that I make the Session and Student columns a composite key. That way I can access a specific record for a particular student for a particular session. Or I can merely get the entire allocation run for a particular session. Questions: Is the idea a good one? How does one implement and query a composite key using SQLAlchemy? What happens to the database if a particular student is not assigned a project (happens if all projects that he wants are taken)? In the code, if a student is not assigned a project, instead of a proj_id he simply gets None for that field/object. I apologise for asking multiple questions but since these are closely-related, I thought I'd ask them in the same space.

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  • php & mySQL: Storing doc, xls, zip, etc. with limited access and archiving

    - by Devner
    Hi all, In my application, I have a provision for users to upload files like doc, xls, zip, etc. I would like to know how to store these files on my website and have only restricted people access it. I may have a group of people and let only these group access those uploaded files. I know that some may try to just copy the link to the document or the file and pass it to another (non-permitted) user and they can download it. So how can I prevent it? How can I check if the request to download the file was made by a legitimate user who has access to the file? The usernames of the group members are stored in the database along with the document name and location in the database so they can access it. But how do I prevent non-permitted users from being able to access that confidential data in all ways? With the above in mind, how do I store these documents? Do I store the documents in a blob column in the Database or just just let user upload to a folder and merely store the path to the file in the database? The security of the documents is of utmost importance. So any procedure that could facilitate this feature would definitely help. I am not into Object Oriented programming so if you have a simpler code that you would like to share with me, I would greatly appreciate it. Also how do I archive documents that are old? Like say there are documents that are 1 year old and I want to conserve my website space by archiving them but still make them available to the user when they need it. How do I go about this? Thank you.

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  • C#; storing a short date in a DateTime object

    - by contactmatt
    I'm trying to store a shortened date (mm/dd/yyyy) into a DateTime object. The following code below is what I am currently trying to do; this includes the time (12:00:00 AM) which I do not want :( DateTime goodDateHolder = Convert.ToDateTime(DateTime.Now.ToShortDateString()); Result will be 10/19/2009 12:00:00 AM

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  • .NET MVC - Storing database result during single page result?

    - by ropstah
    Fairly simple issue which is solved in PHP by using a static variable. private static $pages; public function Pages() { if($pages == null) { $pages = new PageCollection(); $pages->findAll(); } } Everywhere in my code I use Pages()::someFindFunction() to make sure the results are fetched only once, and I use that same collection. I want the same in my .NET MVC application: use something like: <%=MySite.Pages.findById(1).Title%> In the code below, if I use a private variable, or if I use a public class with shared variables (doesn't matter) they are both persisted during the entire application. I want them to load the same way PHP does, once per request. Now where do I store the .NET equivalent of private static $pages, so that the code below works? //what to do with $pages?? Public Module MySite Public Function Pages() As PageCollection If $pages Is Nothing Then $pages.loadAll() End If Return $pages End Function End Module

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  • Lookup site column not saving/storing metadata for Office 2007 documents?

    - by Greg Hurlman
    I'm having this issue on several server environments. We have a list at the site collection root. There is a site column created as a multi-value lookup on that list's Title field. This site column is used in document libraries in subsites as a required field. When we upload anything but an Office 2007 document, the user is presented with the document metadata fill-in screen (EditForm.aspx?Mode=Upload), the user fills in the appropriate data (including picking a value(s) for this lookup), and clicks "check in" - the document is checked in as expected, with the lookup field's value filled in. With an Office 2007 document, this fails. The user selected values for the lookup field do not ever make it to the server - no errors are thrown, but the field is not saved with the document. We have an event listener on these document libraries, and if we inspect the incoming SPListItem on the event listener method before a single line of our code has run, we see that the value for the lookup field is null. It smells like a SharePoint bug to me - but before I go calling Microsoft, has anyone seen this & worked around it? Edit: the only entry I see in the SP trace logs relating to the problem: CMS/Publishing/8ztg/Medium/Got List Item Version, but item was null

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  • Is the Keychain suitable for storing general data, such as strings?

    - by cannyboy
    The Keychain seems to be used a lot for usernames and passwords, but is it a good idea to use it for other sensitive stuff (bank details, ID numbers etc), but with no password? What kind of encryption does the keychain use? The scenario I'm concerned about is a thief acquiring an iPhone (which is screen-locked) and being able to access the file system to get this info. Also, would using the Keychain involve export restrictions due to the use of encryption?

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  • Parsing the json and storing it in an array?

    - by Prateek Raj
    hi everyone, i'm very new to this web related problems, please help i'm working on sencha which proves to be very difficult wen it comes to json parsing . . . . so i'm planning on retrieving the data to the html page and then load it into my js file. . . so here is the problem: i've already asked about it and got a reply.. http://jsbin.com/uwuca5 but now wen i use the html source code locally in my system or even by using the IIS i couldn't parse the data. . . . . . . here is the link for my json file: http://compliantbox.com/optionsedge/sample.php i'm trying to use this link in my code and retrive the data but the data is returning null Please Help Thank you,

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  • Is SQL server the best DB for Storing and comparing images in database for a small ecommerce applica

    - by iecut
    I have been trying to create a small e-commerce web based application using MS Dot Net framework. The application will let the user allow to store the image of their product that they want to sell or purchase, then they will have the option to upload the image of a particular product and compare that image with the similar images in the database. So my two main concerns are: - Is MS SQL a good option to store and compare the images. - Is the any other better database that can do the same work with less complexity of work and that is also easy to integrate with MS dot net framework.

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  • Storing n-grams in database in < n number of tables.

    - by kurige
    If I was writing a piece of software that attempted to predict what word a user was going to type next using the two previous words the user had typed, I would create two tables. Like so: == 1-gram table == Token | NextWord | Frequency ------+----------+----------- "I" | "like" | 15 "I" | "hate" | 20 == 2-gram table == Token | NextWord | Frequency ---------+------------+----------- "I like" | "apples" | 8 "I like" | "tomatoes" | 12 "I hate" | "tomatoes" | 20 "I hate" | "apples" | 2 Following this example implimentation the user types "I" and the software, using the above database, predicts that the next word the user is going to type is "hate". If the user does type "hate" then the software will then predict that the next word the user is going to type is "tomatoes". However, this implimentation would require a table for each additional n-gram that I choose to take into account. If I decided that I wanted to take the 5 or 6 preceding words into account when predicting the next word, then I would need 5-6 tables, and an exponentially increase in space per n-gram. What would be the best way to represent this in only one or two tables, that has no upper-limit on the number of n-grams I can support?

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  • What are the Options for Storing Hierarchical Data in a Relational Database?

    - by orangepips
    Good Overviews One more Nested Intervals vs. Adjacency List comparison: the best comparison of Adjacency List, Materialized Path, Nested Set and Nested Interval I've found. Models for hierarchical data: slides with good explanations of tradeoffs and example usage Representing hierarchies in MySQL: very good overview of Nested Set in particular Hierarchical data in RDBMSs: most comprehensive and well organized set of links I've seen, but not much in the way on explanation Options Ones I am aware of and general features: Adjacency List: Columns: ID, ParentID Easy to implement. Cheap node moves, inserts, and deletes. Expensive to find level (can store as a computed column), ancestry & descendants (Bridge Hierarchy combined with level column can solve), path (Lineage Column can solve). Use Common Table Expressions in those databases that support them to traverse. Nested Set (a.k.a Modified Preorder Tree Traversal) First described by Joe Celko - covered in depth in his book Trees and Hierarchies in SQL for Smarties Columns: Left, Right Cheap level, ancestry, descendants Compared to Adjacency List, moves, inserts, deletes more expensive. Requires a specific sort order (e.g. created). So sorting all descendants in a different order requires additional work. Nested Intervals Combination of Nested Sets and Materialized Path where left/right columns are floating point decimals instead of integers and encode the path information. Bridge Table (a.k.a. Closure Table: some good ideas about how to use triggers for maintaining this approach) Columns: ancestor, descendant Stands apart from table it describes. Can include some nodes in more than one hierarchy. Cheap ancestry and descendants (albeit not in what order) For complete knowledge of a hierarchy needs to be combined with another option. Flat Table A modification of the Adjacency List that adds a Level and Rank (e.g. ordering) column to each record. Expensive move and delete Cheap ancestry and descendants Good Use: threaded discussion - forums / blog comments Lineage Column (a.k.a. Materialized Path, Path Enumeration) Column: lineage (e.g. /parent/child/grandchild/etc...) Limit to how deep the hierarchy can be. Descendants cheap (e.g. LEFT(lineage, #) = '/enumerated/path') Ancestry tricky (database specific queries) Database Specific Notes MySQL Use session variables for Adjacency List Oracle Use CONNECT BY to traverse Adjacency Lists PostgreSQL ltree datatype for Materialized Path SQL Server General summary 2008 offers HierarchyId data type appears to help with Lineage Column approach and expand the depth that can be represented.

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  • Sanitize HTML before storing in the DB or before rendering? (AntiXSS library in ASP.NET)

    - by user102533
    I have an editor that lets users add HTML that is stored in the database and rendered on a web page. Since this is untrusted input, I plan to use Microsoft.Security.Application.AntiXsSS.GetSafeHtmlFragment to sanitize the HTML. Should I santiize before saving to the database or before rendering the untrusted input into the webpage? Is there an advantage in including the AntiXSS source code in my project instead of just the DLL? (Maybe I can customize the white list?) Which class file should I look in for actual implementation of the GetSafeHtmlFragment

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  • Is there a way to increase the efficiency of shared_ptr by storing the reference count inside the co

    - by BillyONeal
    Hello everyone :) This is becoming a common pattern in my code, for when I need to manage an object that needs to be noncopyable because either A. it is "heavy" or B. it is an operating system resource, such as a critical section: class Resource; class Implementation : public boost::noncopyable { friend class Resource; HANDLE someData; Implementation(HANDLE input) : someData(input) {}; void SomeMethodThatActsOnHandle() { //Do stuff }; public: ~Implementation() { FreeHandle(someData) }; }; class Resource { boost::shared_ptr<Implementation> impl; public: Resource(int argA) explicit { HANDLE handle = SomeLegacyCApiThatMakesSomething(argA); if (handle == INVALID_HANDLE_VALUE) throw SomeTypeOfException(); impl.reset(new Implementation(handle)); }; void SomeMethodThatActsOnTheResource() { impl->SomeMethodThatActsOnTheHandle(); }; }; This way, shared_ptr takes care of the reference counting headaches, allowing Resource to be copyable, even though the underlying handle should only be closed once all references to it are destroyed. However, it seems like we could save the overhead of allocating shared_ptr's reference counts and such separately if we could move that data inside Implementation somehow, like boost's intrusive containers do. If this is making the premature optimization hackles nag some people, I actually agree that I don't need this for my current project. But I'm curious if it is possible.

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  • Whats the best data-structure for storing 2-tuple (a, b) which support adding, deleting tuples and c

    - by bhups
    Hi So here is my problem. I want to store 2-tuple (key, val) and want to perform following operations: - keys are strings and values are Integers - multiple keys can have same value - adding new tuples - updating any key with new value (any new value or updated value is greater than the previous one, like timestamps) - fetching all the keys with values less than or greater than given value - deleting tuples. Hash seems to be the obvious choice for updating the key's value but then lookups via values will be going to take longer (O(n)). The other option is balanced binary search tree with key and value switched. So now lookups via values will be fast (O(lg(n))) but updating a key will take (O(n)). So is there any data-structure which can be used to address these issues? Thanks.

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