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  • Efficiently compute the row sums of a 3d array in R

    - by Gavin Simpson
    Consider the array a: > a <- array(c(1:9, 1:9), c(3,3,2)) > a , , 1 [,1] [,2] [,3] [1,] 1 4 7 [2,] 2 5 8 [3,] 3 6 9 , , 2 [,1] [,2] [,3] [1,] 1 4 7 [2,] 2 5 8 [3,] 3 6 9 How do we efficiently compute the row sums of the matrices indexed by the third dimension, such that the result is: [,1] [,2] [1,] 12 12 [2,] 15 15 [3,] 18 18 ?? The column sums are easy via the 'dims' argument of colSums(): > colSums(a, dims = 1) but I cannot find a way to use rowSums() on the array to achieve the desired result, as it has a different interpretation of 'dims' to that of colSums(). It is simple to compute the desired row sums using: > apply(a, 3, rowSums) [,1] [,2] [1,] 12 12 [2,] 15 15 [3,] 18 18 but that is just hiding the loop. Are there other efficient, truly vectorised, ways of computing the required row sums?

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  • How perform USort() on an Array of Objects class definition as a method?

    - by user558724
    class Contact{ public $name; public $bgcolor; public $lgcolor; public $email; public $element; public function __construct($name, $bgcolor, $lgcolor, $email, $element) { $this->name = $name; $this->bgcolor = $bgcolor; $this->lgcolor = $lgcolor; $this->email = $email; $this->element = $element; } public static function sortByName(Contact $p1, Contact $p2) { return strcmp($p1->name, $p2->name); } } class ContactList implements Iterator, ArrayAccess { protected $_label; protected $_contacts = array(); public function __construct($label) { $this->_label = $label; } public function getLabel() { return $this->_label; } public function addContact(Contact $contact) { $this->_contacts[] = $contact; } public function current() { return current($this->_contacts); } public function key() { return key($this->_contacts); } public function next() { return next($this->_contacts); } public function rewind() { return reset($this->_contacts); } public function valid() { return current($this->_contacts); } public function offsetGet($offset) { return $this->_contacts[$offset]; } public function offsetSet($offset, $data) { if (!$data instanceof Contact) throw new InvalidArgumentException('Only Contact objects allowed in a ContactList'); if ($offset == '') { $this->_contacts[] = $data; } else { $this->_contacts[$offset] = $data; } } public function offsetUnset($offset) { unset($this->_contacts[$offset]); } public function offsetExists($offset) { return isset($this->_contacts[$offset]); } public function sort($attribute = 'name') { $sortFct = 'sortBy' . ucfirst(strtolower($attribute)); if (!in_array($sortFct, get_class_methods('Contact'))) { throw new Exception('contact->sort(): Can\'t sort by ' . $attribute); } usort($this->contact, 'ContactList::' . $sortFct); } } public function Sort($property, $asc=true) { // this is where sorting logic takes place $_pd = $this->_contact->getProperty($property); if ($_pd == null) { user_error('Property '.$property.' does not exist in class '.$this->_contact->getName(), E_WARNING); return; } // set sortDescriptor ContactList::$sortProperty = $_pd; // and apply sorting usort($this->_array, array('ContactList', ($asc?'USortAsc':'USortDesc'))); } function getItems(){ return $this->_array; } class SortableItem extends ContactList { static public $sortProperty; static function USortAsc($a, $b) { /*@var $_pd ReflectionProperty*/ /* $_pd = self::$sortProperty; if ($_pd !== null) { if ($_pd->getValue($a) === $_pd->getValue($b)) return 0; else return (($_pd->getValue($a) < $_pd->getValue($b))?-1:1); } return 0; } static function USortDesc($a, $b) { return -(self::USortAsc($a,$b)); } } This approach keeps giving me PHP Warnings: usort() [function.usort]: of all kinds which I can provide later as needed to comment out those methods and definitions in order to test and fix some minor bugs of our program. **$billy parameters are already defined. $all -> addContact($billy); // --> ended up adding each contact manually above $all->Sort('name',true); $items = $all->getItems(); foreach($items as $contact) { echo $contact->__toString(); } $all->sort(); The reason for using usort is to re-arrange the order alphabetically by name but somehow is either stating that the function comparison needs to be an array or another errors which obviously I have seemed to pass. Any help would be greatly appreciated, thanks in advance.

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  • Clean up State field with T-SQL?

    - by Pselus
    The State field in our database is a mess. There was no validation when it was filled so we have everything from two letter abbreviations to full state names to misspelled state names to "test" and "xxxx", etc. I am not going to try to handle everything, but for sure I want to fix the correct state names to abbreviations. I have a list of valid state names and abbreviations, but I don't know how I can do this: UPDATE Table SET State = ('AR','AK') WHERE (SELECT * FROM Table WHERE State IN ('Arkansas','Alaska')) Basically, can I update a field to be something from a list by the location it is in another list?

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  • Naudio - putting audio stream into values [-1,1]

    - by denonth
    Hi all I need to put my audio stream into values of [-1,1]. Can someone tell me a good approach. I was reading byte array and float array from stream but I don't know what to do next. Here is my code: float[] bytes=new float[stream.Length]; float biggest= 0; for (int i = 0; i < stream.Length; i++) { bytes[i] = (byte)stream.ReadByte(); if (bytes[i] > biggest) { biggest=bytes[i]; } } and I don't know how to put values into stream. Because byte is only positive values. And I need to have from [-1,1] for (int i = 0; i < bytes.Count(); i++) { bytes[i] = (byte)(bytes[i] * (1 / biggest)); }

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  • Int[] Reverse - What does this actually do?

    - by Jamie Dixon
    I was just having a play around with some code in LINQPad and noticed that on an int array there is a Reverse method. Usually when I want to reverse an int array I'd do so with Array.Reverse(myIntArray); Which, given the array {1,2,3,4} would then return 4 as the value of myIntArray[0]. When I used the Reverse() method directly on my int array: myIntArray.Reverse(); I notice that myIntArray[0] still comes out as 1. What is the Reverse method actually doing here?

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  • Match an element of an array to a different element in that array

    - by Anh
    I have an array containing several students. I want them to cross-grade one another randomly, i.e. each student will grade someone and will be graded by someone else (these two people may or may not be the same person). Here is my working solution. I'm sure there is a more elegant answer! def randomize(student_array) graders = student_array.dup gradees = student_array.dup result = {} graders.each do |grader| gradee = grader while gradee == grader gradee = gradees.sample end result[grader] = gradee gradees.delete_at(gradees.index(gradee)) end return result end

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  • Android which button index from array was pressed

    - by Tim Wayne
    How do I set up a OnClickListener to simply tell me which index button was pressed from an array of buttons. I can change text and color of these buttons using the array. I set them up like this. TButton[1] = (Button)findViewById(R.id.Button01); TButton[2] = (Button)findViewById(R.id.Button02); TButton[3] = (Button)findViewById(R.id.Button03); up to 36.

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  • need some tips on Drupal $form value

    - by bert
    I got dpm($form) working. Nice! This is much better way to view data. I am still trying to figure out where stuff is coming from eg: location longitude & latitude. The word 'longitude' is referenced in 20 different places. I thought this was a likely place to isolate text box for this input field. dpm($form['#field_info']['field_store_latitude']['location_settings']['form']['fields']); Any tips on how to track down individual input elements?

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  • Why is my PowerShell multi dimensional array being interpreted as a 1 dimensional array?

    - by Jim
    I have the following code: function HideTemplates($File, $Templates) { foreach ($Template in $Templates) { Write-Host $Template[0] $Template[1] $Template[2] } } HideTemplates "test.xml" @(("one", "two", "three")) HideTemplates "test.xml" @(("four", "five", "six"), ("seven", "eight", "nine")) It prints: o n e t w o t h r four five six seven eight nine I want it to print: one two three four five six seven eight nine Am I doing something wrong in my code? Is there a way to force PowerShell to tread a multi-dimensional array with a single item differently?

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  • Resizing a rectangular array

    - by devdept
    Does a smarter way than the following exist to resize a rectangular array? double[,] temp = new double[newSize, originalSecondDimension]; Array.Copy(original, temp, original.Length); I was concerned about duplicating a huge array and the memory necessary to do it. What does the Array.Resize() do internally? Thanks, Alberto

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  • Counting distinct and duplicate attribute values in an array

    - by keruilin
    I have an array of users that's sorted in descending order based on total_points. I need to find the rank of each user in that array. The issue is that more than one user can have the same total points and, thus, the same rank. For example, three users could be in 3rd place with 200 Points. Here's my current code: class Leader < ActiveRecord::Base def self.points_leaders all_leaders = all_points_leaders # returns array of users sorted by total_points in desc order all_leaders_with_rank = [] all_leaders.each do |user| rank = all_leaders.index(user)+1 all_leaders_with_rank << Ldr.new(rank, user) # Ldr is a Struct end return all_leaders_with_rank end end How must I modify the code so that the correct rank is returned, and not just the value of the index position?

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  • Parse a json(?) string using php

    - by passatgt
    I have a string, more specifically, this one: a:16:{s:9:"pseudonym";O:16:"SimpleXMLElement":0:{}s:14:"parallel_title";O:16:"SimpleXMLElement":0:{}s:9:"title_var";O:16:"SimpleXMLElement":0:{}s:6:"series";O:16:"SimpleXMLElement":0:{}s:9:"vol_title";O:16:"SimpleXMLElement":0:{}s:9:"reference";O:16:"SimpleXMLElement":0:{}s:10:"bound_with";O:16:"SimpleXMLElement":0:{}s:15:"general_remarks";O:16:"SimpleXMLElement":0:{}s:6:"copies";O:16:"SimpleXMLElement":1:{i:0;s:1:"1";}s:11:"remarks_BPH";O:16:"SimpleXMLElement":0:{}s:3:"ICN";O:16:"SimpleXMLElement":1:{i:0;s:4:"neen";}s:10:"provenance";O:16:"SimpleXMLElement":0:{}s:7:"binding";O:16:"SimpleXMLElement":0:{}s:10:"size_hxwxd";O:16:"SimpleXMLElement":0:{}s:6:"BookID";O:16:"SimpleXMLElement":1:{i:0;s:4:"6271";}s:5:"repro";O:16:"SimpleXMLElement":0:{}} Is it possible to parse this string somehow? I need to display the keys and values in a list. I tried to use json_decode but it not returns anything, even with the second true parameter(json_decode($string,true))

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  • Jquery Ajax Returned Array - how to handle in Javascript

    - by user232840
    Hi there, If someone could assist me please. I'm doing a jquery Ajax post, for some reason the Json object isn't working so just returning a php array instead $.post ( "classes/RegisterUser.php", $("#frmRegistration").serialize(), function(data) { alert(data); } ); The data is returned to Javascript 100% as array ( [key]=>value [Name] => SomeOneName [Surname] => SomeOneSurName ) How would i go about getting the value of Surname in Javascript? Thanks for your assistance? Regards

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  • Fastest way to represent a collection of bits in PHP?

    - by Piskvor
    What is a good way to represent a collection of bits? I have a set of various on/off toggles (thousands of them) and need to store and retrieve their state. The naïve implementation would be an array of booleans, but I'm wondering if there's a better way (better in terms of access speed and/or memory requirements). I've found this BitArray implementation, but it's limited to 32 bits, which is not enough for this case.

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  • understanding list[i-1] vs list[i]-1

    - by user3720527
    Hopefully this is a simple answer that I am just failing to understand. Full code is public static void mystery(int[] list) { for( int i = list.length - 1; i>1; i --) { if (list[i] > list[i - 1]) { list[i -1] = list[i] - 2; list[i]++; } } } } and lets say we are using a list of [2,3,4]. I know that it will output 2,2,5 but I am unclear how to actually work through it. I understand that the list.length is 3 here, and I understand that the for loop will only run once, but I am very unclear what happens at the list[i - 1] = list[i] - 2; area. Should it be list[2-1] = list[2] - 2? How does the two being outside the bracket effect it differently? Much thanks.

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  • How to create list of numbers and append its reverse to it efficiently in Ruby

    - by Kiwi
    Given a minimum integer and maximum integer, I want to create an array which counts from the minimum to the maximum by two, then back down (again by two, repeating the maximum number). For example, if the minimum number is 1 and the maximum is 9, I want [1, 3, 5, 7, 9, 9, 7, 5, 3, 1]. I'm trying to be as concise as possible, which is why I'm using one-liners. In Python, I would do this: range(1, 10, 2) + range(9, 0, -2) In Ruby, which I'm just beginning to learn, all I've come up with so far is: (1..9).inject([]) { |r, num| num%2 == 1 ? r << num : r }.reverse.inject([]) { |r, num| r.unshift(num).push(num) } Which works, but I know there must be a better way. What is it?

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  • Why does my array initialization code cause a StackOverflowException to be thrown?

    - by MCS
    The following line of code in my class constructor is throwing a StackOverflowException: myList = new string[]{}; // myList is a property of type string[] Why is that happening? And what's the proper way to initialize an empty array? UPDATE: The cause was in the set method, in which I was attempting to trim all values. What's wrong with this code: set { for (int i = 0; i < myList.Length; i++) { if (myList[i] != null) myList[i] = myList[i].Trim(); } }

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  • PHP search multidimensional array for value, then place that element at start of array

    - by BobFlemming
    I need to search this array: cars - [0] -make : Ford -model: Escort -year: 1991 [1] -make: Honda -model: Civic -year: 1996 [2] -make: Vauxhall -model: Astra -year: 1972 And if (for example) the model is "Civic" , place that 'car' at position 0. So the end array would be like: cars - [0] -make: Honda -model: Civic -year: 1996 [1] -make : Ford -model: Escort -year: 1991 [2] -make: Vauxhall -model: Astra -year: 1972 I've tried some usort variations: function typeSort($a, $b) { if ($a['model'] == 'Civic' ) { return 0; } return ($a['model'] < $b['model']) ? -1 : 1; } but this is just returning 1

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  • Add String to adapter

    - by Waggoner_Keith
    I have an adapter and i want to add a string to it but when i run this code it only add the last string in the songstoadd variable ... That is a custom adapter which adds dividers in where neccessary but in the Array Adapter i want to a all of the strings that have the same first letter in their name .... SeparatedListAdapter adapter = new SeparatedListAdapter(this); ArrayList<String> songstoadd = new ArrayList<String>(); Collections.sort(songtitle); int m = 0; while( m <songtitle.size()-1){ if(songtitle.get(m).substring(0, 1) == songtitle.get(m+1).substring(0, 1)){ m++; }else{ songstoadd.clear(); songstoadd.add(songtitle.get(m)); adapter.addSection(songtitle.get(m).substring(0, 1), new ArrayAdapter<String>(getApplicationContext(),R.layout.song, songstoadd)); m++; } } setListAdapter(adapter); }

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  • Adding rows to an array in PHP

    - by ChuckO
    I have loaded an associative array of records from a MySQL database table. The array consists of 1 to 7 rows representing one week of entries, which might not have been entered for each day. How can I insert blank rows into the array for the missing days so that I can easily display the data in a table? I don't need to update the database with the blanks.

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  • adding numeric values of variable number of forms

    - by user306472
    I'm trying to use jquery to loop through a block of forms that contain numeric data and add it all up to be displayed in a form with id grand. I have the ability to dynamically add new forms, so the number of forms I'm looping through will change. Here's my jquery code I wrote that isn't working for whatever reason: $('#table').delegate('input#grand', 'focus', function(){ var grand = $(input.expend).map(function(){ return this.value; }); $(grand).each(function(){ var g = 0; g+= $(this); $('input#grand').val(g); }); });

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  • How to create a dynamic array of an Abstract class?

    - by outsyncof
    Lets say I have an abstract class Cat that has a few concrete subclasses Wildcat, Housecat, etc. I want my array to be able to store pointers to a type of cat without knowing which kind it really is. When I try to dynamically allocate an array of Cat, it doesn't seem to be working. Please help? Cat* catArray = new Cat[200];

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