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  • lambda expressions in VB.NET... what am I doing wrong???

    - by Bob
    when I run this C# code, no problems... but when I translate it into VB.NET it compiles but blows due to 'CompareString' member not being allowed in the expression... I feel like I'm missing something key here... private void PrintButton_Click(object sender, EventArgs e) { if (ListsListBox.SelectedIndex > -1) { //Context using (ClientOM.ClientContext ctx = new ClientOM.ClientContext(UrlTextBox.Text)) { //Get selected list string listTitle = ListsListBox.SelectedItem.ToString(); ClientOM.Web site = ctx.Web; ctx.Load(site, s => s.Lists.Where(l => l.Title == listTitle)); ctx.ExecuteQuery(); ClientOM.List list = site.Lists[0]; //Get fields for this list ctx.Load(list, l => l.Fields.Where(f => f.Hidden == false && (f.CanBeDeleted == true || f.InternalName == "Title"))); ctx.ExecuteQuery(); //Get items for the list ClientOM.ListItemCollection listItems = list.GetItems( ClientOM.CamlQuery.CreateAllItemsQuery()); ctx.Load(listItems); ctx.ExecuteQuery(); // DOCUMENT CREATION CODE GOES HERE } MessageBox.Show("Document Created!"); } } but in VB.NET code this errors due to not being allowed 'CompareString' members in the ctx.Load() methods... Private Sub PrintButton_Click(sender As Object, e As EventArgs) If ListsListBox.SelectedIndex > -1 Then 'Context Using ctx As New ClientOM.ClientContext(UrlTextBox.Text) 'Get selected list Dim listTitle As String = ListsListBox.SelectedItem.ToString() Dim site As ClientOM.Web = ctx.Web ctx.Load(site, Function(s) s.Lists.Where(Function(l) l.Title = listTitle)) ctx.ExecuteQuery() Dim list As ClientOM.List = site.Lists(0) 'Get fields for this list ctx.Load(list, Function(l) l.Fields.Where(Function(f) f.Hidden = False AndAlso (f.CanBeDeleted = True OrElse f.InternalName = "Title"))) ctx.ExecuteQuery() 'Get items for the list Dim listItems As ClientOM.ListItemCollection = list.GetItems(ClientOM.CamlQuery.CreateAllItemsQuery()) ctx.Load(listItems) ' DOCUMENT CREATION CODE GOES HERE ctx.ExecuteQuery() End Using MessageBox.Show("Document Created!") End If End Sub

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  • How to remove words based on a word count

    - by Chris
    Here is what I'm trying to accomplish. I have an object coming back from the database with a string description. This description can be up to 1000 characters long, but we only want to display a short view of this. So I coded up the following, but I'm having trouble in actually removing the number of words after the regular expression finds the total count of words. Does anyone have good way of dispalying the words which are less than the Regex.Matches? Thanks! if (!string.IsNullOrEmpty(myObject.Description)) { string original = myObject.Description; MatchCollection wordColl = Regex.Matches(original, @"[\S]+"); if (wordColl.Count < 70) // 70 words? { uxDescriptionDisplay.Text = string.Format("<p>{0}</p>", myObject.Description); } else { string shortendText = original.Remove(200); // 200 characters? uxDescriptionDisplay.Text = string.Format("<p>{0}</p>", shortendText); } }

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  • How to read pair in freemarker

    - by Lukasz Rys
    Ok i'm having little trouble with reading pair. So I'm creating my pair private Pair<Integer, Integer> count(somethink) { int c1 = 2; int c2 = 4; return new Pair<Integer, Integer>(c1, c2); } And 'sending' it to ftl via java mv.addObject("counted", count(somethink)); I won't write everythink how it sends because I dont think it really matters with my issue. So i'm recieving it in "ftl". Then i was trying to 'read' it <#list counted?keys as key> <a href="#offerOrderTab"><@spring.message "someMsg"/>(${key}/${counted[key]})</a> </#list> After then i'm getting error Expecting a string, date or number here, Expression x is instead a freemarker.ext.beans.SimpleMethodModel As i suppose you dont iterate pairs (or I'm wrong?) i know its pair that contains only one key and one value but still i have to do send it that way and I thought its goin be to similar to iterating through map, in java i would use pair.first() and pair.second() but it doesn't work in ftl (ye i know it shouldnt work). I also tried to cast it to String by using ?string but it didnt work too

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  • Error compiling basic java code

    - by Michael Younani
    New to java. Practicing coding by following a book. Heres my code: class Motorcycle { //Three instance variables - make and color are strings. while a boolean refers to TRUE OR FLASE(in this case off or on) String make; String color; boolean engineState; void startEngine() { if (engineState == true) System.out.print("The engine is already on."); else { engineState = true; System.out.print("The engine is now on."); } void showAtts() { System.out.print("This motorcycle is a " + color + " " + make); if (engineState ==true) System.out.print("The engine is on."); else System.out.print("The engine is off."); } } } When I compile I get 2 errors: 1) illegal start of expression 2) ; expected I can't pin point the problem. If anyone can direct me or hint me please do.

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  • Using the JPA Criteria API, can you do a fetch join that results in only one join?

    - by Shaun
    Using JPA 2.0. It seems that by default (no explicit fetch), @OneToOne(fetch = FetchType.EAGER) fields are fetched in 1 + N queries, where N is the number of results containing an Entity that defines the relationship to a distinct related entity. Using the Criteria API, I might try to avoid that as follows: CriteriaBuilder builder = entityManager.getCriteriaBuilder(); CriteriaQuery<MyEntity> query = builder.createQuery(MyEntity.class); Root<MyEntity> root = query.from(MyEntity.class); Join<MyEntity, RelatedEntity> join = root.join("relatedEntity"); root.fetch("relatedEntity"); query.select(root).where(builder.equals(join.get("id"), 3)); The above should ideally be equivalent to the following: SELECT m FROM MyEntity m JOIN FETCH myEntity.relatedEntity r WHERE r.id = 3 However, the criteria query results in the root table needlessly being joined to the related entity table twice; once for the fetch, and once for the where predicate. The resulting SQL looks something like this: SELECT myentity.id, myentity.attribute, relatedentity2.id, relatedentity2.attribute FROM my_entity myentity INNER JOIN related_entity relatedentity1 ON myentity.related_id = relatedentity1.id INNER JOIN related_entity relatedentity2 ON myentity.related_id = relatedentity2.id WHERE relatedentity1.id = 3 Alas, if I only do the fetch, then I don't have an expression to use in the where clause. Am I missing something, or is this a limitation of the Criteria API? If it's the latter, is this being remedied in JPA 2.1 or are there any vendor-specific enhancements? Otherwise, it seems better to just give up compile-time type checking (I realize my example doesn't use the metamodel) and use dynamic JPQL TypedQueries.

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  • capture text, including tags from string, and then reorder tags with text

    - by Brian
    I have the following text: abcdef<CONVERSION>abcabcabcabc<2007-01-12><name1><2007-01-12>abcabcabcabc<name2><2007-01-11>abcabcabcabc<name3><2007-02-12>abcabcabcabc<name4>abcabcabcabc<2007-03-12><name5><date>abcabcabcabc<name6> I need to use regular expressions in order to clean the above text: The basic extraction rule is: <2007-01-12>abcabcabcabc<name2> I have no problem extracting this pattern. My issue is that within th text I have malformed sequences: If the text doesn't start with a date, and end with a name my extraction fails. For example, the text above may have several mal formed sequences, such as: abcabcabcabc<2007-01-12><name1> Should be: <2007-01-12>abcabcabcabc<name1> Is it possible to have a regular expression that would clean the above, prior to extracting my consistent pattern. In short, i need to find all mal formed patterns, and then take the date tag and put it in front of it, as provided in the example above. Thanks.

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  • Extract information from a Func<bool, T> or alike lambda

    - by Syska
    I''m trying to build a generic cache layer. ICacheRepository Say I have the following: public class Person { public int PersonId { get; set; } public string Firstname { get; set; } public string Lastname { get; set; } public DateTime Added { get; set; } } And I have something like this: list.Where(x => x.Firstname == "Syska"); Here I want to extract the above information, to see if the query supplied the "PersonId" which it did not, so I dont want to cache it. But lets say I run a query like this: list.Where(x => x.PersonId == 10); Since PersonId is my key ... I want to cache it. with the key like "Person_10" and I later can fetch it from the cache. I know its possible to extract the information with Expression<Func<>> but there seems to be a big overhead of doing this (when running compile and extract the Constant values etc. and a bunch of cache to be sure to parse right) Are there a framework for this? Or some smart/golden way of doing this ?

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  • how do i make the app take correct input..?

    - by user1824343
    This is my windows app's one layout which converts Celsius to Fahrenheit. The problem is that when I try to input the temperature it shows some junk(for eg: if i enter '3' it displayin '3.0000009') and sometimes its even showing stack overflow exception. The output is also not shown properly : cel.text is the textbox for celsius. fahre.text is the textbox for fahrenheit. namespace PanoramaApp1 { public partial class FahretoCel : PhoneApplicationPage { public FahretoCel() { InitializeComponent(); } private void fahre_TextChanged(object sender, TextChangedEventArgs e) { if (fahre.Text != "") { try { double F = Convert.ToDouble(fahre.Text); cel.Text = "" + ((5.0/9.0) * (F - 32)) ; //this is conversion expression } catch (FormatException) { fahre.Text = ""; cel.Text = ""; } } else { cel.Text = ""; } } private void cel_TextChanged(object sender, TextChangedEventArgs e) { if (cel.Text != "") { try { Double c = Convert.ToDouble(cel.Text); fahre.Text = "" + ((c *(9.0 / 5.0 )) + 32); } catch (FormatException) { fahre.Text = ""; cel.Text = ""; } } else { fahre.Text = ""; } } } }

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  • in haskell, why do I need to specify type constraints, why can't the compiler figure them out?

    - by Steve
    Consider the function, add a b = a + b This works: *Main> add 1 2 3 However, if I add a type signature specifying that I want to add things of the same type: add :: a -> a -> a add a b = a + b I get an error: test.hs:3:10: Could not deduce (Num a) from the context () arising from a use of `+' at test.hs:3:10-14 Possible fix: add (Num a) to the context of the type signature for `add' In the expression: a + b In the definition of `add': add a b = a + b So GHC clearly can deduce that I need the Num type constraint, since it just told me: add :: Num a => a -> a -> a add a b = a + b Works. Why does GHC require me to add the type constraint? If I'm doing generic programming, why can't it just work for anything that knows how to use the + operator? In C++ template programming, you can do this easily: #include <string> #include <cstdio> using namespace std; template<typename T> T add(T a, T b) { return a + b; } int main() { printf("%d, %f, %s\n", add(1, 2), add(1.0, 3.4), add(string("foo"), string("bar")).c_str()); return 0; } The compiler figures out the types of the arguments to add and generates a version of the function for that type. There seems to be a fundamental difference in Haskell's approach, can you describe it, and discuss the trade-offs? It seems to me like it would be resolved if GHC simply filled in the type constraint for me, since it obviously decided it was needed. Still, why the type constraint at all? Why not just compile successfully as long as the function is only used in a valid context where the arguments are in Num? Thank you.

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  • Project Naming Convention Feedback Please

    - by Sam Striano
    I am creating a ASP.NET MVC 3 application using Entity Framework 4. I am using the Repository/Service Pattern and was looking for feedback. I currently have the following: MVC Application (GTG.dll) GTG GTG.Controllers GTG.ViewModels Business POCO's (GTG.Business.dll) This contains all business objects (Customer, Order, Invoice, etc...) EF Model/Repositories (GTG.Data.dll) GTG.Business (GTG.Context.tt) I used the Entity POCO Generator Templates. GTG.Data.Repositories Service Layer (GTG.Data.Services.dll) GTG.Data.Services - Contains all of the service objects, one per aggregate root. The following is a little sample code: Controller Namespace Controllers Public Class HomeController Inherits System.Web.Mvc.Controller Function Index() As ActionResult Return View(New Models.HomeViewModel) End Function End Class End Namespace Model Namespace Models Public Class HomeViewModel Private _Service As CustomerService Public Property Customers As List(Of Customer) Public Sub New() _Service = New CustomerService _Customers = _Service.GetCustomersByBusinessName("Striano") End Sub End Class End Namespace Service Public Class CustomerService Private _Repository As ICustomerRepository Public Sub New() _Repository = New CustomerRepository End Sub Function GetCustomerByID(ByVal ID As Integer) As Customer Return _Repository.GetByID(ID) End Function Function GetCustomersByBusinessName(ByVal Name As String) As List(Of Customer) Return _Repository.Query(Function(x) x.CompanyName.StartsWith(Name)).ToList End Function End Class Repository Namespace Data.Repositories Public Class CustomerRepository Implements ICustomerRepository Public Sub Add(ByVal Entity As Business.Customer) Implements IRepository(Of Business.Customer).Add End Sub Public Sub Delete(ByVal Entity As Business.Customer) Implements IRepository(Of Business.Customer).Delete End Sub Public Function GetByID(ByVal ID As Integer) As Business.Customer Implements IRepository(Of Business.Customer).GetByID Using db As New GTGContainer Return db.Customers.FirstOrDefault(Function(x) x.ID = ID) End Using End Function Public Function Query(ByVal Predicate As System.Linq.Expressions.Expression(Of System.Func(Of Business.Customer, Boolean))) As System.Linq.IQueryable(Of Business.Customer) Implements IRepository(Of Business.Customer).Query Using db As New GTGContainer Return db.Customers.Where(Predicate) End Using End Function Public Sub Save(ByVal Entity As Business.Customer) Implements IRepository(Of Business.Customer).Save End Sub End Class End Namespace

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  • find, excluding dir, not descending into dir, AND using maxdepth and mindepth

    - by user1680819
    This is RHEL 5.6 and GNU find 4.2.27. I am trying to exclude a directory from find, and want to make sure that directory isn't descended into. I've seen plenty of posts saying -prune will do this - and it does. I can run this command: find . -type d -name "./.snapshot*" -prune -o -print and it works. I run it through strace and verify it is NOT descending into .snapshot. I also want to find directories ONLY at a certain level. I can use mindepth and maxdepth to do this: find . -maxdepth 8 -mindepth 8 -type d and it gives me all the dirs 8 levels down, including what's in .snapshot. If I combine the prune and mindepth and maxdepth options: find . -maxdepth 8 -mindepth 8 -type d \( -path "./.snapshot/*" -prune -o -print \) the output is right - I see all the dirs 8 levels down except for what's in .snapshot, but if I run that find through strace, I see that .snapshot is still being descended into - to levels 1 through 8. I've tried a variety of different combinations, moving the precedence parens around, reording expression components - everything that yields the right output still descends into .snapshot. I see in the man page that -prune doesn't work with -depth, but doesn't say anything about mindepth and maxdepth. Can anyone offer any advice? Thanks... Bill

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  • NSRegularExpression for stripping HTML Tag

    - by Prazi
    I am developing a ebook reader app. I have the .ePUB file for the entire ebook where in each topic of the ebook is a html file. I want to implement the search functionality in the app. I am using NSRegularExpression class for searching. Please consider the following html code: <temp> I am temp in tempo with temptation </temp> Say for example in the above html code I just want to search for the word temp. Now in above code temp is appearing 5 times - <temp> </temp> temp tempo temptation. I am looking for a regular expression where I can only extract the whole word "temp". I don't want to consider the word temp in the html tags <temp> </temp>. I also don't want the word tempo and temptation to be considered. Thanks in advance

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  • C# Linq Select Problem in Method Chain.

    - by Gnought
    Note that the _src inherit IQueryable<U> and V inherit new(); I wrote the following statement, there is no syntax error. IQueryable<V> a = from s in _src where (s.Right - 1 == s.Left) select new V(); But if i re-wrote it as follows, the Visual Studio editor complains an error in the "Select" IQueryable<V> d = _src.Where(s => s.Right - 1 == s.Left).Select(s=> new V()); The Error is: The type arguments cannot be inferred from the usage. Try specifying the type arguments explicitly. Candidates are: System.Collections.Generic.IEnumerable<V> Select<U,V>(this System.Collections.Generic.IEnumerable<U>, System.Func<U,V>) (in class Enumerable) System.Linq.IQueryable<V> Select<U,V>(this System.Linq.IQueryable<U>, System.Linq.Expressions.Expression<System.Func<U,V>>) (in class Queryable) Could anyone explain this phenomenon, and what the solution is to fix the error?

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  • SQL aggregate query question

    - by Phil
    Hi, Can anyone help me with a SQL query in Apache Derby SQL to get a "simple" count. Given a table ABC that looks like this... id a b c 1 1 1 1 2 1 1 2 3 2 1 3 4 2 1 1 ** 5 2 1 2 ** ** 6 2 2 1 ** 7 3 1 2 8 3 1 3 9 3 1 1 How can I write a query to get a count of how may distinct values of 'a' have both (b=1 and c=2) AND (b=2 and c=1) to get the correct result of 1. (the two rows marked match the criteria and both have a value of a=2, there is only 1 distinct value of a in this table that match the criteria) The tricky bit is that (b=1 and c=2) AND (b=2 and c=1) are obviously mutually exclusive when applied to a single row. .. so how do I apply that expression across multiple rows of distinct values for a? These queries are wrong but to illustrate what I'm trying to do... "SELECT DISTINCT COUNT(a) WHERE b=1 AND c=2 AND b=2 AND c=1 ..." .. (0) no go as mutually exclusive "SELECT DISTINCT COUNT(a) WHERE b=1 AND c=2 OR b=2 AND c=1 ..." .. (3) gets me the wrong result. SELECT COUNT(a) (CASE WHEN b=1 AND c=10 THEN 1 END) FROM ABC WHERE b=2 AND c=1 .. (0) no go as mutually exclusive Cheers, Phil.

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  • Magento, 1 db field not saved

    - by david parloir
    Hi there, I have a problem with 1 field of the db. With this code: $expireMonth = Mage::getStoreConfig('points_options/config_points/expiration_period', Mage::app()->getStore()->getId()); if (!is_null($expireMonth) && ($expireMonth > 0)) { $expireDate = date("Y-m-d H:i:s", strtotime("+" . $expireMonth . " month")); } else { $expireDate = NULL; } //die($expireDate); //store in points history table $this->_pointsModel->setCustomerId($this->_customer->getId()) ->setOrdersId('welcome') ->setPointsPending($pointsForNewCustomer) ->setPointsComment(Mage::helper('points')->__('welcome points')) ->setDateAdded(date('Y-m-d H:i:s')) ->setPointsStatus(2)//confirmed ->setPointsType('WE') ->setStoreId(Mage::app()->getStore()->getId()) ->setExpireDate($expireDate) ->save(); every field is saved in the table, except for expire_date. If I uncoment the die($expireData), I see the correct value, something like 2012-01-13 13:21:12. The filed is defined as: `expire_date` datetime NULL Any thaughts? edit: the solution is: $expireDate = date("Y-m-d H:i:s", strtotime("+" . $expireMonth . " months")); check out the "s" in my strtotime expression

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  • Problem Binding to a Brush Property in WPF

    - by Krisc
    Working in WPF, writing a custom user control. I am trying to change the background property of the Border element when I change the value of a property of the class. Right now I am working on simply binding it to a DP, though if there is a better way I am open to suggestions. Here is the XAML for the UserControl <UserControl x:Class="MyProject.MyControl" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" xmlns:d="http://schemas.microsoft.com/expression/blend/2008" xmlns:js="clr-namespace:MyProject" mc:Ignorable="d" x:Name="MyControlRootLayout" Background="Transparent" d:DesignHeight="300" d:DesignWidth="300" Cursor="Hand"> <Border x:Name="RootBorder" Background="{Binding Path=CoreBackground, ElementName=MyControlRootLayout}" > </Border> </UserControl> And the code... public partial class MyControl : UserControl { public static DependencyProperty IsSelectedProperty = DependencyProperty.Register("IsSelected", typeof(bool), typeof(MyControl)); public static DependencyProperty CoreBackgroundProperty = DependencyProperty.Register("CoreBackground", typeof(Brush), typeof(MyControl)); public MyControl() { CoreBackground = new SolidColorBrush(Color.FromArgb(0, 255, 245, 104)); InitializeComponent(); Margin = new Thickness(5); } public Brush CoreBackground { get { return (Brush)GetValue(CoreBackgroundProperty); } set { SetValue(CoreBackgroundProperty, value); } } public bool IsSelected { get { return (bool)GetValue(IsSelectedProperty); } private set { SetValue(IsSelectedProperty, value); } } } Instead, the background comes out as transparent.

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  • Safari & Frames in html

    - by user575838
    Hi, I am using Windows Expression web to design a embedded quicktime player that plays 4 separate videos in a main frame. Yes, I am using frames. Header Frame, Left Bar frame, Footer & Main centre frame. Everything works in Explorer as it should. See the picture ![Web Frames preview in Explorer, links work, link plays dif videos when clicked.][1] <html> Untitled 1 <div style="position: absolute; width: 100px; height: 100px; z-index: 1" id="layer1"> </div> <p>This page uses frames, but your browser doesn&#39;t support them.</p> </body> </noframes> When I check it in Safari, the video is misaligned in the frame & the background color is black, which I want it white. All the links work, it's just the misalignment & background color. See the picture. ![Safari Preview][2] Firefox also works. Here's the code, page source from the Safari browser. Heres a pic of Safari misalignment. Heres the Safari Code code Please help. It may be simple but I'm a newb. I appreciate any advice from you pro's.

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  • How to evaluate json member using variable ?

    - by Miftah
    Hi i've got a problem evaluating json. My goal is to insert json member value to a function variable, take a look at this function func_load_session(svar){ var id = ''; $.getJSON('data/session.php?load='+svar, function(json){ eval('id = json.'+svar); }); return id; } this code i load session from php file that i've store beforehand. i store that session variable using dynamic var. <?php /* * format ?var=[nama_var]&val=[nilai_nama_var] */ $var = $_GET['var']; $val = $_GET['val']; $load = $_GET['load']; session_start(); if($var){ $_SESSION["$var"] = $val; echo "Store SESSION[\"$var\"] = '".$_SESSION["$var"]."'"; }else if($load){ echo $_SESSION["$load"]; } ?> using firebug, i get expected response but i also received error uncaught exception: Syntax error, unrecognized expression: ) pointing at this eval('id = json.'+svar); i wonder how to solve this

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  • How does Haskell do pattern matching without us defining an Eq on our data types?

    - by devoured elysium
    I have defined a binary tree: data Tree = Null | Node Tree Int Tree and have implemented a function that'll yield the sum of the values of all its nodes: sumOfValues :: Tree -> Int sumOfValues Null = 0 sumOfValues (Node Null v Null) = v sumOfValues (Node Null v t2) = v + (sumOfValues t2) sumOfValues (Node t1 v Null) = v + (sumOfValues t1) sumOfValues (Node t1 v t2) = v + (sumOfValues t1) + (sumOfValues t2) It works as expected. I had the idea of also trying to implement it using guards: sumOfValues2 :: Tree -> Int sumOfValues2 Null = 0 sumOfValues2 (Node t1 v t2) | t1 == Null && t2 == Null = v | t1 == Null = v + (sumOfValues2 t2) | t2 == Null = v + (sumOfValues2 t1) | otherwise = v + (sumOfValues2 t1) + (sumOfValues2 t2) but this one doesn't work because I haven't implemented Eq, I believe: No instance for (Eq Tree) arising from a use of `==' at zzz3.hs:13:3-12 Possible fix: add an instance declaration for (Eq Tree) In the first argument of `(&&)', namely `t1 == Null' In the expression: t1 == Null && t2 == Null In a stmt of a pattern guard for the definition of `sumOfValues2': t1 == Null && t2 == Null The question that has to be made, then, is how can Haskell make pattern matching without knowing when a passed argument matches, without resorting to Eq?

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  • Determining presence of prototype with correct return type

    - by R..
    Here's a random problem in C black magic I just came up with: Write a function that returns 1 if malloc has been prototyped to return a pointer type and 0 if malloc has a return type of int (either implicitly or due to wrong prototype), without invoking any implementation-defined or undefined behavior. I believe it's solvable, but I haven't worked out the solution. Note that calling the function cannot be necessary and in fact is not possible since calling a function with the incorrect prototype is undefined behavior. I have some ideas for ingredients but I think it makes for a better puzzle (and possibly more diverse ideas) if I leave them out for now. I don't need the solution for any immediate use, but it could be handy in configure scripts and such. Update: A better example of the usefulness (with strdup instead of malloc): #undef strdup #define strdup(x) (strdup_has_proto ? strdup((x)) : my_strdup((x))) i.e. being able to implement X_has_proto as an expression at the source level could be a portable way to use functions which a system might or might not have, and fall back on a local replacement, without needing any separate configure step.

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  • Solving problems with near infinite potential solutions

    - by Zonda333
    Today I read the following problem: Use the digits 2, 0, 1, 1 and the operations +, -, x, ÷, sqrt, ^ , !, (), combinations, and permutations to write equations for the counting numbers 1 through 100. All four digits must be used in each expression. Only the digits 2, 0, 1, 1 may be used, and each must be used exactly once. Decimals may be used, as in .1, .02, etc. Digits may be combined; numbers such as 20 or 101 may be used. Example: 60 = 10*(2+1)!, 54 = ¹¹C2 - 0! Though I was able to quickly find around 50 solutions quite easily in my head, I thought programming it would be a far superior solution. However, I then realized I had no clue how to go about solving a problem like this. I am not asking for complete code for me to copy and paste, but for ideas about how I would solve this problems, and others like it that have nearly infinite potential solutions. As I will be writing it in python, where I have the most experience, I would prefer if the answers were more python based, but general ideas are great too.

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  • ReplaceAll not working as expected

    - by Tim Kemp
    Still early days with Mathematica so please forgive what is probably a very obvious question. I am trying to generate some parametric plots. I have: ParametricPlot[{ (a + b) Cos[t] - h Cos[(a + b)/b t], (a + b) Sin[t] - h Sin[(a + b)/b t]}, {t, 0, 2 \[Pi]}, PlotRange -> All] /. {a -> 2, b -> 1, h -> 1} No joy: the replacement rules are not applied and a, b and h remain undefined. If I instead do: Hold@ParametricPlot[{ (a + b) Cos[t] - h Cos[(a + b)/b t], (a + b) Sin[t] - h Sin[(a + b)/b t]}, {t, 0, 2 \[Pi]}, PlotRange -> All] /. {a -> 2, b -> 1, h -> 1} it looks like the rules ARE working, as confirmed by the output: Hold[ParametricPlot[{(2 + 1) Cos[t] - 1 Cos[(2 + 1) t], (2 + 1) Sin[t] - 1 Sin[(2 + 1) t]}, {t, 0, 2 \[Pi]}, PlotRange -> All]] Which is what I'd expect. Take the Hold off, though, and the ParametricPlot doesn't work. There's nothing wrong with the equations or the ParametricPlot itself, though, because I tried setting values for a, b and h in a separate expression (a=2; b=1; h=1) and I get my pretty double cardoid out as expected. So, what am I doing wrong with ReplaceAll and why are the transformation rules not working? This is another fundamentally important aspect of MMA that my OOP-ruined brain isn't understanding. I tried reading up on ReplaceAll and ParametricPlot and the closest clue I found was that "ParametricPlot has attribute HoldAll and evaluates f only after assigning specific numerical values to variables" which didn't help much or I wouldn't be here. Thanks.

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  • Showing a MKAnnotation for custom object

    - by Chamanhm
    I have a list of objects and each of those has a title, name, description, latitude, longitude and address. Is it possible to show this objects as MKAnnotations? I've been stuck with this for hours now. When I tried to make the objects have a CLLocationCoordinate2D I kept getting the error about latitude or longitude not being assignable. #import <Foundation/Foundation.h> #import <MapKit/MapKit.h> @interface Oficina : NSObject <MKMapViewDelegate> @property (nonatomic, readwrite) CLLocationCoordinate2D oficinaCoordinate; @property (nonatomic, strong) NSString *oficinaCiudad; @property (nonatomic, strong) NSString *oficinaEstado; @property (nonatomic, strong) NSString *oficinaTitulo; @property (nonatomic, strong) NSString *oficinaTelefono; @property (nonatomic, strong) NSString *oficinaLatitud; @property (nonatomic, strong) NSString *oficinaLongitud; @property (nonatomic, strong) NSString *oficinaID; @property (nonatomic, strong) NSString *oficinaDireccion; @property (nonatomic, strong) NSString *oficinaHorario; @property (nonatomic, strong) NSString *oficinaTipoDeOficina; @property (nonatomic, strong) NSString *oficinaServicios; @property (nonatomic, strong) NSString *oficinaTipoDeModulo; @end So after consuming an internet service I get around 70 of these objects. Now I want to be able to turn each of those into a map annotation. This is one of the ways I've tried to assign the latitude but I get the error "Expression not assignable".. currentOffice.oficinaCoordinate.latitude = [parseCharacters floatValue]; Where currentOffice is an instance of my custom object.

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  • Coding the R-ight way - avoiding the for loop

    - by mropa
    I am going through one of my .R files and by cleaning it up a little bit I am trying to get more familiar with writing the code the r-ight way. As a beginner, one of my favorite starting points is to get rid of the for() loops and try to transform the expression into a functional programming form. So here is the scenario: I am assembling a bunch of data.frames into a list for later usage. dataList <- list (dataA, dataB, dataC, dataD, dataE ) Now I like to take a look at each data.frame's column names and substitute certain character strings. Eg I like to substitute each "foo" and "bar" with "baz". At the moment I am getting the job done with a for() loop which looks a bit awkward. colnames(dataList[[1]]) [1] "foo" "code" "lp15" "bar" "lh15" colnames(dataList[[2]]) [1] "a" "code" "lp50" "ls50" "foo" matchVec <- c("foo", "bar") for (i in seq(dataList)) { for (j in seq(matchVec)) { colnames (dataList[[i]])[grep(pattern=matchVec[j], x=colnames (dataList[[i]]))] <- c("baz") } } Since I am working here with a list I thought about the lapply function. My attempts handling the job with the lapply function all seem to look alright but only at first sight. If I write f <- function(i, xList) { gsub(pattern=c("foo"), replacement=c("baz"), x=colnames(xList[[i]])) } lapply(seq(dataList), f, xList=dataList) the last line prints out almost what I am looking for. However, if i take another look at the actual names of the data.frames in dataList: lapply (dataList, colnames) I see that no changes have been made to the initial character strings. So how can I rewrite the for() loop and transform it into a functional programming form? And how do I substitute both strings, "foo" and "bar", in an efficient way? Since the gsub() function takes as its pattern argument only a character vector of length one.

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  • How to parse mathematical expressions involving parentheses

    - by Rob P.
    Please forgive my title, I really don't know how to phrase it better. This isn't a school assignment or anything, but I realize it's a mostly academic question. But, what I've been struggling to do is parse 'math' text and come up with an answer. For Example - I can figure out how to parse '5 + 5' or '3 * 5' - but I fail when I try to correctly chain operations together. (5 + 5) * 3 It's mostly just bugging me that I can't figure it out. If anyone can point me in a direction, I'd really appreciate it. EDIT Thanks for all of the quick responses. I'm sorry I didn't do a better job of explaining. First - I'm not using regular expressions. I also know there are already libraries available that will take, as a string, a mathematical expression and return the correct value. So, I'm mostly looking at this because, sadly, I don't "get it". Second - What I've tried doing (is probably misguided) but I was counting '(' and ')' and evaluating the deepest items first. In simple examples, this worked; but my code is not pretty and more complicated stuff crashes. When I 'calculated' the lowest level, I was modifying the string. So... (5 + 5) * 3 Would turn into 10 * 3 Which would then evaluate to 30 But it just felt 'wrong'. I hope that helps clarify things. I'll certainly check out the links provided.

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