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  • Ideas Related to Subset Sum with 2,3 and more integers

    - by rolandbishop
    I've been struggling with this problem just like everyone else and I'm quite sure there has been more than enough posts to explain this problem. However in terms of understanding it fully, I wanted to share my thoughts and get more efficient solutions from all the great people in here related to Subset Sum problem. I've searched it over the Internet and there is actually a lot sources but I'm really willing to re-implement an algorithm or finding my own in order to understand fully. The key thing I'm struggling with is the efficiency considering the set size will be large. (I do not have a limit, just conceptually large). The two phases I'm trying to implement ideas on is finding two numbers that are equal to given integer T, finding three numbers and eventually K numbers. Some ideas I've though; For the two integer part I'm thing basically sorting the array O(nlogn) and for each element in the array searching for its negative value. (i.e if the array element is 3 searching for -3). Maybe a hash table inclusion could be better, providing a O(1) indexing the element? For the three or more integers I've found an amazing blog post;http://www.skorks.com/2011/02/algorithms-a-dropbox-challenge-and-dynamic-programming/. However even the author itself states that it is not applicable for large numbers. So I was for 2 and 3 and more integers what ideas could be applied for the subset problem. I'm struggling with setting up a dynamic programming method that will be efficient for the large inputs as well.

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  • Row selection based on subtable data in MySQL

    - by Felthragar
    I've been struggling with this selection for a while now, I've been searching around StackOverflow and tried a bunch of stuff but nothing that helps me with my particular issue. Maybe I'm just missing something obvious. I have two tables: Measurements, MeasurementFlags "Measurements" contain measurements from a device, and each measurement can have properties/attributes attached to them (commonly known as "flags") to signify that the measurement in question is special in some way or another (for instance, one flag may signify a test or calibration measurement). Note: One record per flag! Right, so a record from the "Measurements" table can theoreticly have an unlimited amount of MeasurementFlags attached to it, or it can have none. Now, I need to select records from "Measurements", that have an attached "MeasurementFlag" valued "X", but it must also NOT have a flag valued "Y" attached to it. We're talking about a fairly large database with hundreds of millions of rows, which is why I'm trying to keep all of this logic within one query. Splitting it up would create too many queries, however if it's not possible to do in one query I guess I don't have a choise. Thanks in advance.

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  • Should a Trim method generally in the Data Access Layer or with in the Domain Layer?

    - by jpierson
    I'm dealing with a database that contains data with inconsistencies such as white leading and trailing white space. In general I see a lot of developers practice defensive coding by trimming almost all strings that come from the database that may have been entered by a user at some point. In my oppinoin it is better to do such formating before data is persisted so that it is done only once and then the data can be in a consistent and reliable state. Unfortunatley this is not the case however which leads me to the next best solution, using a Trim method. If I trim all data as part of my data access layer then I don't have to concern myself with defensive trimming within the business objects of my domain layer. If I instead put the trimming responsibility in my business objects, such as with set accessors of my C# properties, I should get the same net results however the trim will be operating on all values assigned to my business objects properties not just the ones that come from the inconsistent database. I guess as a somewhat philisophical question that may determine the answer I could ask "Should the domain later be responsible for defensive/coercive formatting of data?" Would it make sense to have a set accessor for a PhoneNumber property on a business object accept a unformatted or formatted string and then attempt to format it as required or should this responsibility be pushed to the presentation and data access layers leaving the domain layer more strict in the type of data that it will accept? I think this may be the more fundamental question. Update: Below are a few links that I thought I should share about the topic of data cleansing. Information service patterns, Part 3: Data cleansing pattern LINQ to SQL - Format a string before saving? How to trim values using Linq to Sql?

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  • Autmatically create table on MySQL server based on date?

    - by Anthony
    Is there an equivalent to cron for MySQL? I have a PHP script that queries a table based on the month and year, like: SELECT * FROM data_2010_1 What I have been doing until now is, every time the script executes it does a query for the table, and if it exists, does the work, if it doesn't it creates the table. I was wondering if I can just set something up on the MySQL server itself that will create the table (based on a default table) at the stroke of midnight on the first of the month. Update Based on the comments I've gotten, I'm thinking this isn't the best way to achieve my goal. So here's two more questions: If I have a table with thousands of rows added monthly, is this potentially a drag on resources? If so, what is the best way to partition this table, since the above is verboten? What are the potential problems with my home-grown method I originally thought up?

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  • problem during data modification

    - by nectar
    here my code - if($pin == '105') { $sqltree = "INSERT INTO tbltree (`userId`, `level`, `superId`, `rootId`, `childcount`) VALUES ('$child1', '1', '$newid', '$myroot', '0');"; mysql_query($sqltree); update_level($newid); } function update_level() { //for 1st level $newid = $_SESSION['newid']; //getting senior's level 1 and to increase by 1 $sqlgetlevel = "SELECT superId,level1 FROM tbltree WHERE userID='$newid'"; echo "<br>test:".$sqlgetlevel; $result = mysql_query($sqlgetlevel,$link)or die(mysql_error()); //line 340 $row = mysql_fetch_array($result, MYSQL_ASSOC); $level1 = $row["level1"]; $level1 = $level1 + 1; //update increased level $sqlupdate = "UPDATE tbltree SET level1='$level1' WHERE userId='$newid';"; mysql_query($sqlupdate,$link)or die(mysql_error()); //change superId for new level $superid = $row["superId"]; } ERROR - test:SELECT superId,level1 FROM tbltree WHERE userID='29277640' Warning: mysql_query() expects parameter 2 to be resource, null given in C:\xampp\htdocs\303\levelupdate.php on line 340

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  • How to index a table with a Type 2 slowly changing dimension for optimal performance

    - by The Lazy DBA
    Suppose you have a table with a Type 2 slowly-changing dimension. Let's express this table as follows, with the following columns: * [Key] * [Value1] * ... * [ValueN] * [StartDate] * [ExpiryDate] In this example, let's suppose that [StartDate] is effectively the date in which the values for a given [Key] become known to the system. So our primary key would be composed of both [StartDate] and [Key]. When a new set of values arrives for a given [Key], we assign [ExpiryDate] to some pre-defined high surrogate value such as '12/31/9999'. We then set the existing "most recent" records for that [Key] to have an [ExpiryDate] that is equal to the [StartDate] of the new value. A simple update based on a join. So if we always wanted to get the most recent records for a given [Key], we know we could create a clustered index that is: * [ExpiryDate] ASC * [Key] ASC Although the keyspace may be very wide (say, a million keys), we can minimize the number of pages between reads by initially ordering them by [ExpiryDate]. And since we know the most recent record for a given key will always have an [ExpiryDate] of '12/31/9999', we can use that to our advantage. However... what if we want to get a point-in-time snapshot of all [Key]s at a given time? Theoretically, the entirety of the keyspace isn't all being updated at the same time. Therefore for a given point-in-time, the window between [StartDate] and [ExpiryDate] is variable, so ordering by either [StartDate] or [ExpiryDate] would never yield a result in which all the records you're looking for are contiguous. Granted, you can immediately throw out all records in which the [StartDate] is greater than your defined point-in-time. In essence, in a typical RDBMS, what indexing strategy affords the best way to minimize the number of reads to retrieve the values for all keys for a given point-in-time? I realize I can at least maximize IO by partitioning the table by [Key], however this certainly isn't ideal. Alternatively, is there a different type of slowly-changing-dimension that solves this problem in a more performant manner?

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  • Find order of data inside an array

    - by user271619
    I have a simple array of stuff: $array = array("apples","oranges","strawberries"); I am trying to find the order of the stuff inside the array. (sometimes the order changes, and so do the items) I'm expecting to get something like this: "apples" = 0, "oranges = 1, "strawberries = 2 The end result has something to do with database sorting. Something like this, inside a foreach loop: UPDATE tbl SET sortorder = $neworder WHERE fruit = '$fruitname' The $neworder variable would be populated with the new order, inside the array. While the $fruit variable comes from the item inside the array.

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  • How should my application keep clients in sync with schema changes to HTML5 databases?

    - by Chad Johnson
    I'm wanting to incorporate HTML5 database storage into my web application to make it online-accessible. I've done lots of development in server-side environments with databases, and we all know that database schema additions and modifications are often necessary. I am wondering what should happen if my application uses an offline database schema, and that schema changes. How do I prevent the application from breaking on the client side? How do I ensure the database is always up to date on the client end? Anyone have any solutions?

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  • IIS 7 Can't read data from ASP.Net application services tables

    - by vikp
    Hi, I'm working on deploying a web application written in C# with ASP.Net Application services databases. The application runs fine on the development machine. Windows Server 2003 has been built to test the application. The database has been scripted across using MS SQL Server GUI. ASP.Net application services tables were created using an utility. The connection strings are stored in the web.config and connectionStrings.config. The application connects to the database successfully, but then it times out after 10 seconds.

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  • Hierarchical data table for JSF2 and RichFaces

    - by Iravanchi
    I'm using RichFaces on my JSF2 application, and I need a way to have something like a tree-column or tree-table. As far as I know, there's no support for such thing in RichFaces. Something's mentioned for RichFaces 4.0, but the priority of this in their plan isn't promising at all, and I don't think that it's going to be included in 4.0. I know there's a tree table available in IceFaces, but I'd rather not add another library to avoid conflicts and learning curve and ... So, I'm looking for the simplest way that I can achieve the same results with minimum efforts, maybe using sub-tables in RichFaces? Any ideas would be appreciated.

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  • LINQ Data Context Not Showing Methods

    - by CccTrash
    For some reason my DataContext is not showing all the normal methods like SubmitChanges() etc in the intellisense. It also won't compile if I type in db.SubmitChanges(); Any idea what I'm doing wrong? Normally I don't have this issue, I have several other projects that work fine... Image of what I'm talking about:

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  • How to display specific data from a file

    - by user1067332
    My program is supposed to ask the user for firstname, lastname, and phone number till the users stops. Then when to display it asks for the first name and does a search in the text file to find all info with the same first name and display lastname and phones of the matches. import java.util.*; import java.io.*; import java.util.Scanner; public class WritePhoneList { public static void main(String[] args)throws IOException { BufferedWriter output = new BufferedWriter(new FileWriter(new File( "PhoneFile.txt"), true)); String name, lname, age; int pos,choice; try { do { Scanner input = new Scanner(System.in); System.out.print("Enter First name, last name, and phone number "); name = input.nextLine(); output.write(name); output.newLine(); System.out.print("Would you like to add another? yes(1)/no(2)"); choice = input.nextInt(); }while(choice == 1); output.close(); } catch(Exception e) { System.out.println("Message: " + e); } } } Here is the display code, when i search for a name, it finds a match but displays the last name and phone number of the same name 3 times, I want it to display all of the possible matches with the first name. import java.util.*; import java.io.*; import java.util.Scanner; public class DisplaySelectedNumbers { public static void main(String[] args)throws IOException { String name; String strLine; try { FileInputStream fstream = new FileInputStream("PhoneFile.txt"); // Get the object of DataInputStream DataInputStream in = new DataInputStream(fstream); BufferedReader br = new BufferedReader(new InputStreamReader(in)); Scanner input = new Scanner(System.in); System.out.print("Enter a first name"); name = input.nextLine(); strLine= br.readLine(); String[] line = strLine.split(" "); String part1 = line[0]; String part2 = line[1]; String part3 = line[2]; //Read File Line By Line while ((strLine= br.readLine()) != null) { if(name.equals(part1)) { // Print the content on the console System.out.print("\n" + part2 + " " + part3); } } }catch (Exception e) {//Catch exception if any System.out.println("Error: " + e.getMessage()); } } }

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  • How to direct people to fill out a form

    - by Solmead
    What is the best way to get people to fill out a form correctly? For instance I originally had a "Name" field on a form and I want 1 person per form. People filled it out like this: "Mark & Becky Newsman". So I broke it into 2 fields, "First Name" and "Last Name", And people are still filling it out wrong, like "First Name" = "Mark & Becky", "Last Name" = "Newsman". Are there any recommendations on how better to get people to understand that only one person's name should go there? I currently have it on two lines, would it work better to put both fields on one line? If this is on the wrong site go ahead and move it to the correct site.

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  • algorithm for checking addresses for matches?

    - by user151841
    I'm working on a survey program where people will be given promotional considerations the first time they fill out a survey. In a lot of scenarios, the only way we can stop people from cheating the system and getting a promotion they don't deserve is to check street address strings against each other. I was looking at using levenshtein distance to give me a number to measure similarity, and consider those below a certain threshold a duplicate. However, if someone were looking to game the system, they could easily write "S 5th St" instead of "South Fifth Street", and levenshtein would consider those strings to be very different. So then I was thinking to convert all strings to a 'standard address form' i.e. 'South' becomes 's', 'Fifth' becomes '5th', etc. Then I was thinking this is hopeless, and too much effort to get it working robustly. Is it? I'm working with PHP/MySql, so I have the limitations inherent in that system.

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  • Qt – How to add calculated column in QsqlRelationalTableModel ?

    - by user289175
    I have an table view showed part description, quantity, price And I have a Model/View using this code model = new QSqlRelationalTableModel(this); model->setTable("parts"); model->setRelation(3,QSqlRelation("part_tbl","part_id","part_desc")); model->select(); ui->tableView->setModel(model); I need to add a new column that shows quantity * price in the table view. It's important to know I'm using QsqlRelationalTableModel Help is appreciated, Thanks in advance

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  • Java MapReduce read data

    - by Tatiana
    Hi I am having following map-reduce code by which I am trying to read records from my database. There's code: import java.io.*; import java.util.ArrayList; import java.util.List; import org.apache.hadoop.fs.*; import org.apache.hadoop.io.*; import org.apache.hadoop.mapred.*; import org.apache.hadoop.mapred.lib.db.DBConfiguration; import org.apache.hadoop.mapred.lib.db.DBInputFormat; import org.apache.hadoop.mapred.lib.db.DBWritable; import org.apache.hadoop.util.*; import org.apache.hadoop.conf.*; public class Connection extends Configured implements Tool { public int run(String[] args) throws IOException { JobConf conf = new JobConf(getConf(), Connection.class); conf.setInputFormat(DBInputFormat.class); DBConfiguration.configureDB(conf, "com.sun.java.util.jar.pack.Driver", "jdbc:postgresql://localhost:5432/polyclinic", "postgres", "12345"); String[] fields = { "name" }; DBInputFormat.setInput(conf, MyRecord.class, "doctors", null, null, fields); conf.setMapOutputKeyClass(LongWritable.class); conf.setMapOutputValueClass(MyRecord.class); conf.setOutputKeyClass(LongWritable.class); conf.setOutputValueClass(TextOutputFormat.class); TextOutputFormat.setOutputPath(conf, new Path(args[0])); JobClient.runJob(conf); return 0; } public static void main(String[] args) throws Exception { int exitCode = ToolRunner.run(new Connection(), args); System.exit(exitCode); } } Class Mapper: import java.io.IOException; import org.apache.hadoop.io.IntWritable; import org.apache.hadoop.io.LongWritable; import org.apache.hadoop.io.Text; import org.apache.hadoop.mapred.MapReduceBase; import org.apache.hadoop.mapred.Mapper; import org.apache.hadoop.mapred.OutputCollector; import org.apache.hadoop.mapred.Reporter; public class MyMapper extends MapReduceBase implements Mapper<LongWritable, MyRecord, Text, IntWritable> { public void map(LongWritable key, MyRecord val, OutputCollector<Text, IntWritable> output, Reporter reporter) throws IOException { output.collect(new Text(val.name), new IntWritable(1)); } } Class Record: import java.io.DataInput; import java.io.DataOutput; import java.io.IOException; import java.sql.PreparedStatement; import java.sql.ResultSet; import java.sql.SQLException; import org.apache.hadoop.io.Text; import org.apache.hadoop.io.Writable; import org.apache.hadoop.mapred.lib.db.DBWritable; class MyRecord implements Writable, DBWritable { String name; public void readFields(DataInput in) throws IOException { this.name = Text.readString(in); } public void readFields(ResultSet resultSet) throws SQLException { this.name = resultSet.getString(1); } public void write(DataOutput out) throws IOException { } public void write(PreparedStatement stmt) throws SQLException { } } After this I got error: WARN mapred.JobClient: No job jar file set. User classes may not be found. See JobConf(Class) or JobConf#setJar(String). Can you give me any suggestion how to solve this problem?

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  • How to convert a table column to another data type

    - by holden
    I have a column with the type of Varchar in my Postgres database which I meant to be integers... and now I want to change them, unfortunately this doesn't seem to work using my rails migration. change_column :table1, :columnB, :integer So I tried doing this: execute 'ALTER TABLE "table1" ALTER COLUMN "columnB" TYPE integer USING CAST(columnB AS INTEGER)' but cast doesn't work in this instance because some of the column are null... any ideas?

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  • DMX Analysis Services question

    - by user282382
    Hi, I am have two mining models, both are time series. One is [Company_Inputs] and the other is [Booking_Projections]. What I want to do is use EXTEND_MODEL_CASES to join the results of [Company_Inputs] as the extended cases. So basically something like: Select Flattened PredictTimeSeries([Bookings], 1, 6, EXTEND_MODEL_CASES) FROM [Booking_Projections] Natural Prediction Join (Select Flattened PredictTimeSeries([Metric1], 1, 6) From [Company_Inputs]) AS T This code of course doesn't work, but the idea is to use the predictions made from [Company_Inputs] as cases for predicting future values of [Booking_Projections] If anyone has an idea of how I can accomplish this I would appreciate it very much.

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  • retrieve comma delimited data from a field in using SQL

    - by Nichols
    I've created a form in php that collects basic information. I have a list box that allows multiple items selected (ie housing, rent, food, water). If multiple items are selected they are stored in a field called Needs seperated by a comma. I have created a report ordered by the persons needs. The people who only have one need are sorted correctly, but the people who have multiple are sorted exactly as the string passed to the database (ie. housing, rent, food, water) -- which is not what i want. Is there a way to seperate the multiple values in this field using SQL to count each need instance/occurance as 1 so that there are no comma delimitations shown in the results? CLICK FOR EXAMPLE

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  • Get the Grid data in ColumnHeaderClick

    - by plotnick
    Sorrry guys, I'm stuck here. I have a few grids, I also have CollectionViewSource objects associated with those grids. Now, I'm trying to apply CollectionViewSource.SortDescriptions in ColumnHeaderClick method, and now I have to define almost the same method for each grid. But the only thing I really need is to obtain in which Grid is happenning. How to get that, I have no idea. Help me please. VisualTreeHelper.GetParent didn't work.

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  • Insert data into SQL server with best performance

    - by Incognito
    I have an application which intensively uses DB (SQL Server). As it must have high performance I would like to know the fastest way to insert record into DB.Fastest from the standpoint of execution time. What should I use ? As I know the fastest way is to create stored procedure and to call it from code (ADO.NET). Please let me know is there any better way or may be there are is some other practices to increase performance.

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  • Dynamic Hierarchical Javascript Object Loop

    - by user1684586
    var treeData = {"name" : "A", "children" : [ {"name" : "B", "children": [ {"name" : "C", "children" :[]} ]} ]}; THE ARRAY BEFORE SHOULD BE EMPTY. THE ARRAY AFTER SHOULD BE POPULATED DEPENDING ON THE NUMBER OF NODES NEEDED THAT WILL BE DEFINED FROM A DYNAMIC VALUE THAT IS PASSED. I would like to build the hierarchy dynamically with each node created as a layer/level in the hierarchy having its own array of nodes. THIS SHOULD FORM A TREE STRUCTURE. This is hierarchy structure is described in the above code. This code has tree level simple for demonstrating the layout of the hierarchy of values. There should be a root node, and an undefined number of nodes and levels to make up the hierarchy size. Nothing should be fixed besides the root node. I do not need to read the hierarchy, I need to construct it. The array should start {"name" : "A", "children" : []} and every new node as levels would be created {"name" : "A", "children" : [HERE-{"name" : "A", "children" : []}]}. In the child array, going deeper and deeper. Basically the array should have no values before the call, except maybe the root node. After the function call, the array should comprise of the required nodes of a number that may vary with every call. Every child array will contain one or more node values. There should be a minimum of 2 node levels, including the root. It should initially be a Blank canvas, that is no predefined array values.

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