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  • DataTable C# Empty column type

    - by Dested
    I am trying build a DataTable one row at a time using the following code. foreach (var e in Project.ProjectElements[hi.FakeName].Root.Elements()) { index = 0; object[] obj=new object[count]; foreach (var holdingColumn in names) { string d = e.Attribute(holdingColumn.Key).Value; obj[index++] = d; } dt.Rows.Add(obj); } The problem is the DataTable has types tied to the columns. Sometimes im passing null (or an empty string) in that object index and it is telling me that it cant be converted properly to a DateTime (in this case). My question is what should I default this value to, or is there some way to have the DataTable ignore empty values.

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  • Power Law distribution for a given exponent in C# using MathNet

    - by Eric Tobias
    Hello! I am currently working on a project where I need to generate multiple values (floats or doubles preferably) that follow a power law distribution with a given exponent! I was advised to use the MathNet.Iridium library to help me. The problem I have is that the documentation is not as explicit as it should be if there is any! I see multiple distributions that fit the general idea of the power law distribution but I cannot pinpoint a good distribution to use with a certain exponent as a parameter. Does anybody have more experience in that matter and could give me some hints or advice?

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  • How to select difference using sql?

    - by ganuke
    I wrote a sql query to retrieve data as follows: SELECT (MAX (b.filledqty) - MAX (a.filledqty)) AS filledtoday FROM clientordermas a, clientordermas b WHERE a.clordid = 'w9110126' AND b.clordid = 'w9110126' AND (SELECT max(a.price) FROM clientordermas a WHERE a.clordid = 'w9110126') < 1000; There are three records in the table for the given clordid with price values 800, 900 1200. So, what I need is to get the difference between 1200 and 900 which is 300. But, the above statement always returns 0. What I should get is MAX (b.filledqty) retuns 1200 and MAX (a.filledqty) retuns 900. But it is not happening. This is not the exact problem I am facing but a simplified version of it. Can someone please help?

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  • Guiding a Robot Through a Path

    - by Hamza Yerlikaya
    I have a field filled with obstacles, I know where they are located, and I know the robot's position. Using a path-finding algorithm, I calculate a path for the robot to follow. Now my problem is, I am guiding the robot from grid to grid but this creates a not-so-smooth motion. I start at A, turn the nose to point B, move straight until I reach point B, rinse and repeat until the final point is reached. So my question is: What kind of techniques are used for navigating in such an environment so that I get a smooth motion? The robot has two wheels and two motors. I change the direction of the motor by turning the motors in reverse. EDIT: I can vary the speed of the motors basically the robot is an arduino plus ardumoto, I can supply values between 0-255 to the motors on either direction.

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  • Convert date time value to expected with SimpleDateFormat

    - by Khoi Nguyen
    I have an issue with converting a date time value to expected one with SimpleDateFormat (java), my expected format is MM/yyyy, and I want to convert 2 values to only 1 format MM-yyyy for example 05-2012 yyyy-MM for example 2012-05 ouput is 05/2012. I implemented something look like following String expiry = "2012-01"; try { result = convertDateFormat(expiry, "MM-yyyy", expectedFormat); } catch (ParseException e) { try { result = convertDateFormat(expiry, "yyyy-MM", expectedFormat); } catch (ParseException e1) { e1.printStackTrace(); } e.printStackTrace(); } private String convertDateFormat(String date, String oPattern, String ePattern) throws ParseException { SimpleDateFormat normalFormat = new SimpleDateFormat(oPattern); Date d = normalFormat.parse(date); SimpleDateFormat cardFormat = new SimpleDateFormat(ePattern); return cardFormat.format(d); } Now, the return value is 6808, I don't know why. Kindly anyone help me on this case.

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  • Entity Framework - avoiding another query

    - by adamjellyit
    I have a requirement to only save data to a table in a database (I don't need to read it) If the record already exists I want to update it otherwise I will add it. It usually exists. My entity context might already hold the object .. if it does I want to find it and use it again without causing it to refresh from the database when I 'find' it i.e. The context holds a collection of entities (rows of a database) I want to find an entity in the collection and only want the context to go to the database if entity is not in the collection. I don't care about the current values of the entity .. I just want to update them. Hope this is clear ..... thanks

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  • Weird mapping error in linq-to-sql dbml file in VS2010

    - by rwwilden
    Since I switched to VS2010, several times a day I get a compilation error in my dbml file: DBML1005: Mapping between DbType 'bigint' and Type 'MyNamespace.SecurityToken' in Column 'SecurityToken' of Type 'Employee' is not supported When I restart VS2010 the error disappears. I have no problems running my application using this dbml file (specifically, there are no problems getting correct values inside the SecurityToken property of Employee objects). The SecurityToken property is of an enum type defined as follows: [Flags] public enum SecurityToken : long { None = 1, Admin = 2, ...... } The SecurityToken column in the database is of type bigint. Am I missing something? It's especially weird that the error only happens sometimes, when I'm writing code that isn't related at all to the LINQ model.

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  • Parametrize the WHERE clause?

    - by ControlFlow
    Hi, stackoverflow! I'm need to write an stored procedure for SQL Server 2008 for performing some huge select query and I need filter it results with specifying filtering type via procedure's parameters (parameterize where clause). I found some solutions like this: create table Foo( id bigint, code char, name nvarchar(max)) go insert into Foo values (1,'a','aaa'), (2,'b','bbb'), (3,'c','ccc') go create procedure Bar @FilterType nvarchar(max), @FilterValue nvarchar(max) as begin select * from Foo as f where case @FilterType when 'by_id' then f.id when 'by_code' then f.code when 'by_name' then f.name end = case @FilterType when 'by_id' then cast(@FilterValue as bigint) when 'by_code' then cast(@FilterValue as char) when 'by_name' then @FilterValue end end go exec Bar 'by_id', '1'; exec Bar 'by_code', 'b'; exec Bar 'by_name', 'ccc'; But it doesn't work when the columns has different data types... It's possible to cast all the columns to nvarchar(max) and compare they as strings, but I think it will cause a performance degradation... Is it possible to parameterize where clause in stored procedure without using things like EXEC sp_executesql (dynamic SQL and etc.)?

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  • PDF Generation Help needed

    - by Kobojunkie
    Hi, I am brandnew to PDF Generation or rendering but have a project to, create a PDF Template system that allows users to save Template to Database, and later generate a PDF document using the template and values from my database. Questions a) Is there a PDF tool out there that can help me with this and documentation I can study to learn of this? b) Are there free tools out there for this? c) How do I create a PDF Template? XML? Thanks in Advance!

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  • Transactional isolation level needed for safely incrementing ids

    - by Knut Arne Vedaa
    I'm writing a small piece of software that is to insert records into a database used by a commercial application. The unique primary keys (ids) in the relevant table(s) are sequential, but does not seem to be set to "auto increment". Thus, I assume, I will have to find the largest id, increment it and use that value for the record I'm inserting. In pseudo-code for brevity: id = select max(id) from some_table id++ insert into some_table values(id, othervalues...) Now, if another thread started the same transaction before the first one finished its insert, you would get two identical ids and a failure when trying to insert the last one. You could check for that failure and retry, but a simpler solution might be setting an isolation level on the transaction. For this, would I need SERIALIZABLE or a lower level? Additionally, is this, generally, a sound way of solving the problem? Are the any other ways of doing it?

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  • c# Generic List

    - by user177883
    I m populating data for different entities into set of lists using generic lists as follows : List<Foo> foos .. List<Bar> bars .. I need to write these lists to a file, i do have a util method to get the values of properties etc. using reflection. What i want to do is: using a single method to write these into files such as: void writeToFile(a generic list) { //Which i will write to file here. } How can i do this? I want to be able to call : writeToFile(bars); writeToFile(foos);

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  • Best way to store sales tax information

    - by Seph
    When designing a stock management database system (sales / purchases) what would be the best way to store the various taxes and other such amounts? A few of the fields that could be saved are: Unit price excluding tax Unit price including tax Tax per item Total excluding tax (rounded to 2 decimals) Total including tax (rounded to 2 decimals) Total tax (rounded to 2 decimals) Currently the most reasonable solution so far is storing down (roughly) item, quantity, total excluding tax (rounded) and the total tax (rounded). Can anyone suggest some better way of storing this details for a generic system? Also, given the system needs to be robust, what should be done if there were multiple tax values (eg: state and city) which might need to be separated, in this case a separate table would be in order, but would it be considered excessive to just have a rowID and some taxID mapping to a totalTax column?

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  • After installing VS 2010 - Generic Host Process For Win32 Services problem starts.

    - by Muhammad Kashif Nadeem
    After installing VS 2010 trial I am getting this error "Generic Host Process For Win32 Services Encountered A Problem and needs to close. When this message pops my computer just stuck and I can not even restart it normally. I have found one fix on net but after that fix I can not access my LAN. This fix change these values in registry. HKLM\SYSTEM\CurrentControlSet\Services\netbt\parameters TransportBindName HKLM\Software\Microsoft\OLE EnableDCOM If I revert these registry changes then I again start getting 'Generic Host Process For Win32 Services' I have uninstall VS 2010 but this problem persist. This problem is not because of any virus. Any help to fix this or I have to re install Windows. Thanks.

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  • HSQLDB Constraint Violation & SQL Query Log for an HSQLDB in-memory setup

    - by shipmaster
    We have a setup where we are using an embedded HSQLDB for backing Hibernate/JPA unit tests in java, and we are using the in-memory database mode since we simply want the database thrown away after the test run. My problem is that one of the tests is failing due to a constraint violation and HSQLDB lists the column as SYS_CT_286, and the query that appears in the log is the prepared statement where I cant see what the actual parameter values are (they are replaced by '?'). My questions are: 1- Is there a way in which I can see the actual SQL being executed? (like the mysql query log for example?). 2- What exactly is SYS_CT_286? it is not one of my columns, is it a generated column? is there something obvious that may be wrong with it? Thanks.

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  • How to reload a table view in a view controller in iphone?

    - by Warrior
    I am new to iphone development.I have created a table view in a view controller. I want to reload the table view so that i can display the contents which are parsed previously in delegates. More over reloadData does only reload the cells. It doesn't take care of actually updating the underlying datasource. E.g. if i read data from an array in tableView:cellForRowAtIndexPath:, I have to change the array values befor calling reloadData. How can i achieve this. Please help me out.Thanks.

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  • Eta/Eta-squared routines in R

    - by aL3xa
    Apart from graphical estimation of linearity (gaze-at-scatterplot method), which is utilized before applying some technique from GLM family, there are several ways to do this estimation arithmetically (i.e. without graphs). Right now, I'll focus on Fisher's eta-squared - correlation ratio: arithmetically, it's equal to squared Pearson's r (coef. of determination: R2) if relationship between two variables is linear. Hence, you can compare values of eta and r and make an assessment about type of relation (linear or not). It provides an information about percent of variance in the dependent variable explained (linearly or not) by the independent variable. Therefore, you can apply it when linearity assumptions are not met. Simply stated: is there a routine for eta/eta-squared in R?

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  • Weird behavior of std::vector

    - by Nima
    I have a class like this: class OBJ{...}; class A { public: vector<OBJ> v; A(int SZ){v.clear(); v.reserve(SZ);} }; A *a = new A(123); OBJ something; a->v.push_back(something); This is a simplified version of my code. The problem is in debug mode it works perfect. But in release mode it crashes at "push_back" line. (with all optimization flags OFF) I debugged it in release mode and the problem is in the constructor of A. the size of the vector is something really big with dummy values and when I clear it, it doesn't change... Do you know why? Thanks,

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  • How do I mock memory allocation failures ?

    - by Andrei Ciobanu
    I want to extensively test some pieces of C code for memory leaks. On my machine I have 4 Gb of RAM, so it's very unlikely for a dynamic memory allocation to fail. Still I want to see the comportment of the code if memory allocation fails, and see if the recover mechanism is "strong" enough. What do you suggest ? How do I emulate an environment with lower memory specs ? How do i mock my tests ? EDIT: I want my tests to be code independent. I only have "access" to return values for different functions in the library I am testing. I am not supposed to write "test logic" inside the code I am testing.

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  • Building a rails form to filter an index page?

    - by Schroedinger
    G'day guys, I'm having an issue with filtering the presentation of several thousand trade items I have in my system. As per the specs of the system we're building we have to have a form that allows people to put in a start date and then an interval in minutes, to filter the presentation of the items. I've built my helper functions to return all of the trades within that interval period, but I can't for the life of me properly build the form that will return a dateTime value and an integer value within the top of the index page? Any ideas? Would I have to build a separate model object to assign values to, or is there a simpler way?

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  • try...else...except syntax error

    - by iform
    I can't understand this... Cannot get this code to run and I've no idea why it is a syntax error. try: newT.read() #existingArtist = newT['Exif.Image.Artist'].value #existingKeywords = newT['Xmp.dc.subject'].value except KeyError: print "KeyError" else: #Program will NOT remove existing values newT.read() if existingArtist != "" : newT['Exif.Image.Artist'] = artistString print existingKeywords keywords = os.path.normpath(relativePath).split(os.sep) print keywords newT['Xmp.dc.subject'] = existingKeywords + keywords newT.write() except: print "Cannot write tags to ",filePath Syntax error occurs on the last "except:". Again...I have no idea why python is throwing a syntax error (spent ~3hrs on this problem).

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  • How to order a TimeZone list in .NET?

    - by reallyJim
    I have an ASP.NET web application that requires users to select their appropriate time zone so that it can correctly show local times for events. In creating a simple approach for selecting the time zone, I started by just using the values from TimeZoneInfo.GetSystemTimeZones(), and showing that list. The only problem with this is that since our application is primarily targeted at the United States, I'd like to show those entries first, basically starting with Eastern Time and working backwards (West) until I reach Atlantic time. What's a good approach to do this in code?

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  • Inspect in memory hsqldb while debugging

    - by Albert
    We're using hdsqldb in memory to run junit tests which operate against a database. The db is setup before running each test via a spring configuration. All works fine. Now when a tests fails it can be convinient to be able to inspect the values in the in memory database. Is this possible? If so how? Our url is: jdbc.url=jdbc:hsqldb:mem:testdb;sql.enforce_strict_size=true The database is destroyed after each tests. But when the debugger is running the database should also still be alive. I've tried connecting with the sqldb databaseManager. That works, but I don't see any tables or data. Any help is highly appreciated!

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  • Why is my asp.net mvc form POSTing instead of GETting?

    - by quakkels
    My code is straightforward enough: <% using(Html.BeginForm(FormMethod.Get)) %> <% { %> Search for in Screen Name and Email: <%: Html.TextBox("keyword", Request.QueryString["keyword"]) %> <button type=submit>Search</button> <% } %> The issue I'm running into is that when I submit this form, the values are not added to the querystring. Instead, it appears that the form is submitting by a post request. When I look at the generated HTML, I have this: <form action="/find/AdminMember/MemberList" method="post"> Search for in Screen Name and Email: <input id="keyword" name="keyword" type="text" value="" /> <button type=submit>Search</button> </form> Does anyone know why? This seems pretty simple and straighforward to me.

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  • Entity-attribute-value model using codeigniter / php

    - by John Stewart
    SO I am trying to create a way to structure my database to be able customize forms. I looked into EAV pattern and here is my db structure: Table form - form_id - form_name - form_added_on - form_modified_at Table: form_fields - field_id - form_id - field_type (TEXT, RADIO etc..) - field_default_value - field_required Table: form_data - data_id - field_id - form_id - field_value so now I can store any custom form into the database and if I want to get the values for an individual form I can simply join it by "form_id" .. the problem: I want to be able to search through all the forms for a specific field value. How can I do that with EAV model? Also, I thought about just storing the custom data as a serialized (JSON) object but then I am not sure how can I query that data. Please note that I am using Codeigniter with MYSQL. So if conversation can use Codeigniter libraries if needed.

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  • When is referential integrity not appropriate?

    - by Curtis Inderwiesche
    I understand the need to have referential integrity for limiting specific values on entry or possibly preventing them from removal upon a request of deletion. However, I am unclear as to a valid use case which would exclude this mechanism from always being used. I guess this would fall into several sub-questions: When is referential integrity not appropriate? Is it appropriate to have fields containing multiple and/or possibly incomplete subsets of a foreign key's list? Typically, should this be a schema structure design decision or an interface design decision? (Or possibly neither or both) Thoughts?

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