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• Can I have an android activity run only on the first time an application is opened?

  - by The Trav

  OK, so I'm playing around with an android app. The 90% use case is that users want to go straight to the primary list screen to find what they're looking for. That's what I want as my default screen. The first time a user loads the app however, some configuration is required before their list screen is of any value to them. So my question, is how I can go about displaying the configuration activity the first time the app is opened up, and then the list screen for future openings. I also want to put a demo button on the configuration screen, so I suppose more than just detecting that it's the first time, I specifically want to detect whether the user has performed certain configurations within the first screen.

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• Scala updating/creating value in a hashmap

  - by user1672739

  I don't understand this with Scala hasmaps: How do I create a value or update one if it does not exist? I am tryng to count the number of characters in a list of Strings. I've tried this code but it doesn't work : def times(chars: List[Char]): List[(Char, Int)] = { val map = new HashMap[Char, Int]() chars.foreach( (c : Char) => { map.update(c, map.get(c) + 1) }) } I understand the returning type isn't correct. But is my foreach loop wrong? Is there a prettier way to write it?

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• Where to declare variable? C#

  - by user1303781

  I am trying to make an average function... 'Total' adds them, then 'Total' is divided by n, the number of entries... No matter where I put 'double Total;', I get an error message. In this example I get... Use of unassigned local variable 'Total' If I put it before the comment, both references show up as error... I'm sure it's something simple..... namespace frmAssignment3 { class StatisticalFunctions { public static class Statistics { //public static double Average(List<MachineData.MachineRecord> argMachineDataList) public static double Average(List<double> argMachineDataList) { double Total; int n; for (n = 1; n <= argMachineDataList.Count; n++) { Total = argMachineDataList[n]; } return Total / n; } public static double StDevSample(List<MachineData.MachineRecord> argMachineDataList) { return -1; } } } }

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• Programmatically get valid switch/case values

  - by craigim

  When MATLAB scans through cases in a switch/case block, does it remember the values that it skips, and is it possible to access that list? I have a few functions with long switch\case block and I would like to have them return a list of valid case values if they make it down to otherwise. For instance, I have a function that returns a set of optical constants for a material. It currently has about 20 different materials and it is growing as I consider new ones. I realize I can brute-force it and just re-type all of the valid cases into a cell array under otherwise and have the function throw an error and return the list of valid responses, but maintaining both lists without errors or laziness creeping in over time is challenging.

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• Missing MethodInfo for overloaded function with different return type

  - by Charvak

  I have a class defined as follows interface ITest { List<T> Find<T>(int i); } class Test: ITest { public T List<T> Find<T>(int i) { return default(T); } List<T> ITest.Find<T>(int i) { return null; } } When I use typeof(Test).GetMethods() (both with and without appropriate BindingFlags) I do not get the MethodInfo for ITest.Find function. What is the best way of getting the MethodInfo for the missing method? Thanks

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• Definition of "lisp form"?

  - by josh

  Hi, What exactly the definition of a "Lisp form"? As far as I know, it's "either an atom or a list that has a symbol as its first element". But then, this (in Scheme) would not be a form: ((lambda () 42)) ;; The answer to Life, the Universe and Everything. Because the first element of the list is itself another list. And after it's evaluated it will be a procedure (not a symbol). I can find several different websites and tutorials talking about Lisp forms, but none which gives a complete and detailed definition. Where can I find one?

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• Write a tree class in Java where each level has a unique object type

  - by user479576

  I need to write a tree class in Java where each level has a unique object type. The way it is written below does not take advantage of generics and causes alot of duplicate code. Is there a way to write this with Generics ? public class NodeB { private String nodeValue; //private List<NodeB> childNodes; // constructors // getters/setters } public class NodeA { private String value; private List<NodeB> childNodes; // constructors // getters/setters } public class Tree { private String value; private List<NodeA> childNodes; // constructors // tree methods }

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• Can someone please clarify the Birthday Effect for me?

  - by Mark

  Please help interpret the Birthday effect as described in Wikipedia: A birthday attack works as follows: Pick any message m and compute h(m). Update list L. Check if h(m) is in the list L. if (h(m),m) is already in L, a colliding message pair has been found. else save the pair (h(m),m) in the list L and go back to step 1. From the birthday paradox we know that we can expect to find a matching entry, after performing about 2^(n/2) hash evaluations. Does the above mean 2^(n/2) iterations through the above entire loop (i.e. 2^(n/2) returns to step 1), OR does it mean 2^(n/2) comparisons to individual items already in L.

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• Manually manipulating ArrayList

  - by jsan

  I have an assignment where I have to create a deque, however I am not allowed to use any built-in classes or interfaces. I am implementing my deque using an array list. My problem is that when I have to, for instance, add to the beginning of the array list (beginning of the queue), i am not allowed to do this: public void addFirst(ArrayList<Integer> array) { array.add(0, int); } Is there a way to do this without using the add() function? Such as manually adding to the front and shifting the rest of the array to the right? Or maybe creating a new array list and copying...I'm not sure. Any help would be great; I have a bunch of functions to write, and getting the first one done will definitely put me in the right direction. Thanks

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• Search box inside a div. Django

  - by Juliette Dupuis

  In my django app I display a list of elements (friends name) thanks to a loop: <div> {% for friend in group %} <p>{{ friend.name }} <p> {% endfor %} </div> I would like to create a search box on the top of my list in order to be able to find only the friends the user wants. I would like the search bar does not need to click to send the request (an example is the Airtime searchbox on top of the facebook friends list). I have absolutely no idea on how to do that, and I'm looking for hints or tips to start. Thank you very much for your help.

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• Data Structure Brushup (Java)

  - by Daddy Warbox

  This should be easy for many of you, but for me it's just another bit of rust needing to be chipped away as I get back into basic Java coding. Using bloody associative arrays for so long in other languages have turned me nice and spoiled. :P My problem is simple: I'm storing a set of objects, each containing a string and a number, in a list. I would like each object inserted into this list to be sorted alphabetically by its string. I would also like to be able to retrieve objects from the list by their string as well. I would like to do this as formally and/or efficiently as possible. Is there something already available in the Java standard libraries for this?

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• Test Redirection with RSpec and Capybara (Rails)

  - by balanv

  I just have learnt how cool RSpec and Cabybara is, and now working around it to learn writing actual test. I am trying to check if after clicking a link, there is a redirection to a specific page. Below is the scenario 1) I have a page /projects/list - I have an anchor with html "Back" and it links to /projects/show Below is the test i wrote in rspec describe "Sample" do describe "GET /projects/list" do it "sample test" do visit "/projects/list" click_link "Back" assert_redirected_to "/projects/show" end end end The test fails with a failure message like below Failure/Error: assert_redirected_to "/projects/show" ArgumentError: @request must be an ActionDispatch::Request Please suggest me on how i should test the redirection and what am i doing wrong?

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• Looking for Haskell `group` alternative in F#

  - by Heather

  Haskell group descripted there: http://www.haskell.org/ghc/docs/latest/html/libraries/base/Data-List.html#v:group example : group "Mississippi" = ["M","i","ss","i","ss","i","pp","i"] Is there simple F# way of doing it? I can implement something alike let rec sameCounter (data : list<float>) el same (ss : list<float * int>) = if data.Length > (el + 1) then if data.[el] = data.[el + 1] then sameCounter data (el + 1) <| same + 1 <| ss else if same > 0 then sameCounter data (el + 1) <| 0 <| (data.[el], same) :: ss else sameCounter data (el + 1) <| 0 <| ss else ss let group d = sameCounter d 0 0 [] but it's a bit ugly way I think, is there better variant?

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• C# Generic new() constructor problem

  - by LB

  I'm trying to create a new object of type T via its constructor when adding to the list. I'm getting a compile error: The correct error message is: 'T': cannot provide arguments when creating an instance of a variable But it does! Any ideas? public static string GetAllItems<T>(...) where T : new() { ... List<T> tabListItems = new List<T>(); foreach (ListItem listItem in listCollection) { tabListItems.Add(new T(listItem)); // error here. } ... }

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• Data binding of itemscontrol in Silverlight 3.0

  - by jmkarthik

  I am trying to define an itemscontrol and data bind it to a List and the code is as below. XAML Item Class public class Item { public string val; } XAML.cs public MainPage() { InitializeComponent(); List<Item> items = new List<Item>(); Item item1 = new Item(); item1.val = "iasl;fdj1"; items.Add(item1); Item item2 = new Item(); item2.val = "iasfdkasdkljf2"; items.Add(item2); ic.ItemsSource = items; } The items are displayed when I run this. Am I missing something?

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• Error reading file with accented vowels

  - by Daniel Dcs

  The following statement to fill a list from a file : action = [] with open (os.getcwd() + "/files/" + "actions.txt") as temp:          action = list (temp) gives me the following error: (result, consumed) = self._buffer_decode (data, self.errors, end) UnicodeDecodeError: 'utf-8' codec can not decode byte 0xf1 in position 67: invalid continuation byte if I add errors = 'ignore': action = [] with open (os.getcwd () + "/ files /" + "actions.txt", errors = 'ignore') as temp:          action = list (temp) Is read the file but not the ñ and vowels accented á-é-í-ó-ú being that python 3 works, as I have understood, default to 'utf-8' I'm looking for a solution for two or more days, and I'm getting more confused. In advance thank you very much for any suggestions.

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• C#: reading in a text file more 'intelligently'

  - by DarthSheldon

  I have a text file which contains a list of alphabetically organized variables with their variable numbers next to them formatted something like follows: aabcdef 208 abcdefghijk 1191 bcdefga 7 cdefgab 12 defgab 100 efgabcd 999 fgabc 86 gabcdef 9 h 11 ijk 80 ... ... I would like to read each text as a string and keep it's designated id# something like read "aabcdef" and store it into an array at spot 208. The 2 issues I'm running into are: I've never read from file in C#, is there a way to read, say from start of line to whitespace as a string? and then the next string as an int until the end of line? given the nature and size of these files I do not know the highest ID value of each file (not all numbers are used so some files could house a number like 3000, but only actually list 200 variables) So how could I make a flexible way to store these variables when I don't know how big the array/list/stack/etc.. would need to be.

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• Select All options and Disable not working in IE

  - by user1096909

  I'm having an issue in IE8 multiselect we are using jQuery to selectall and disable the list. List is being disabled but not selected and the same scenario is working perfectly in FireFox where the entire list is selected and disable Can anyone help me how to handle this issue in IE Thanks in advance Below is my code: <select name="weekdays" id="weekdays" disabled="disabled" multiple> <option value="Monday">Monday </option> <option value="Tuesday">Tuesday</option> <option value="Wednesday">Wednesday</option> <option value="Thursday">Thursday </option> <option value="Friday">Friday</option> <option value="Saturday">Saturday</option> <option value="Sunday">Sunday</option> </select>

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• speeding up parsing of files

  - by user248237

  the following function parses a CSV file into a list of dictionaries, where each element in the list is a dictionary where the values are indexed by the header of the file (assumed to be the first line.) this function is very very slow, taking ~6 seconds for a file that's relatively small (less than 30,000 lines.) how can I speed it up? def csv2dictlist_raw(filename, delimiter='\t'): f = open(filename) header_line = f.readline().strip() header_fields = header_line.split(delimiter) dictlist = [] # convert data to list of dictionaries for line in f: values = map(tryEval, line.strip().split(delimiter)) dictline = dict(zip(header_fields, values)) dictlist.append(dictline) return (dictlist, header_fields) thanks.

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• foreach statement (get string values)

  - by nhoyti

  Can someone please help me out? My code for splitting the strings is working however, i still need to use the splitted string my page. How can i achieve this? Here's my current code private void SplitStrings() { List<string> listvalues = new List<string>(); listvalues = (List<string>)Session["mylist"]; string[] strvalues = listvalues.ToArray(); if (listvalues != null) { foreach (string strElement in listvalues) { string[] prods = strElement.ToString().Split("|".ToCharArray()); string prodName = prods[0].ToString(); Response.Write(prodName); } } } link text how can i replace the response.write with any label or literal? when i tried to use a literal on the code it displays one single string not all of the strings that's been splitted. any ideas?

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• Linq - Grouping where items fall in multiple groups?

  - by PirateKitten

  Is it possible using Linq to create a group where items fall into more than one group? Using the following trivial example: public class Data { public string ID; public int From; public int To; } And this list: List<Data> data = new List<Data>() { new Data() { ID = "A", From = 1, To = 3 }, // Call this A new Data() { ID = "B", From = 1, To = 2 }, // Call this B new Data() { ID = "C", From = 2, To = 3 } // Call this C }; I'd like to group by each possible integer in the ranges From and To (though instead of finding the min + max I could supply the query with the range I want, for example 1 to 3), and in each group would be a reference to the Data instance where the grouping int fits in its range. Hard to explain, easier to show each group and the instances I'd expect in each: [Group 1] 1 - A, B [Group 2] 2 - A, B, C [Group 3] 3 - A, C Is this possible? Or must groups be mutually exclusive?

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• CSS: How to set remaining width as %, but having knowledge of only pixels

  - by Mega Matt

  Hi all, I've seen this question asked in a couple other contexts on SO, but I thought it would be worth asking again for my particular case. I'm trying to create some re-usable CSS classes for more consistency and less clutter on my site, and I'm stuck on trying to standardize one thing I use frequently. I have a container div that I don't want to set the height for (because it will vary depending on where on the site it is), and inside it is a header div, and then an unordered list of items, all with CSS applied to them. It looks a lot like this: I want the unordered list to take up the remaining room in the container div, knowing that the header div is 18px tall. I just don't know how to specify the list's height as "the result of 100% minus 18px". Does anyone have any advice in this situation? Thanks very much.

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• Deleting the first occurrence of a target in aList [closed]

  - by Bandz Jooz

  /** Replaces each occurrence of oldItem in aList with newItem */ public static void replace(List<Student> aList, Student oldItemStudent newItem) { int index = aList.indexOf(oldItem); while(index != -1){ aList.set(index, newItem); index = aList.indexOf(oldItem); } /** Deletes the first occurrence of target in aList */ public static void delete(List<Student> aList, Student target){ Object o = //stuck here, dont know how to set up boolean stuff } } I figured out how to do the first method by looking up Java documentation, however I can't figure out how to finish my code for the second method even though I looked up the documentation which states: boolean remove(Object o) Removes the first occurrence of the specified element from this list, if it is present.

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• problem with Expression not equal types

  - by user428547

  class first { private int? firstID; } class second { private int secondID; private int secondField; } public override Expression<Func<first, bool>> FirstFilter() { Contex db = new Contex(); List<second> list = (from p in db.second select p).ToList(); return b => list.Select(p => p.secondID).Contains(b.firstID); } and i have error: cannot convert from 'System.Collections.Generic.IEnumerable' to 'System.Collections.Generic.IEnumerable' i have tried many diferent ways, but i just don't know how can i fix it.

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• Getting Error 91

  - by user1695788

  I have a general comprehension issue with classes and objects. What I'm trying to do is pretty simple but I'm getting errors. In the code example below, sometimes the line "Call tables.MethodInCTables" runs fine and sometimes it produces error 91, object not set. IN all cases, I can "see" the method in the type ahead so I know that the code recognizes the "tables" instance and "sees" MethodInCTables. But then I get the run-time error. Sub MainSub() Dim tables as New CTables Call tables.MethodInCTables End Sub ----Class Module = CTables Sub MethodInCTables() ...do something End Sub

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