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• Implementing Naïve Bayes algorithm in Java - Need some guidance

  - by techventure

  hello stackflow people As a School assignment i'm required to implement Naïve Bayes algorithm which i am intending to do in Java. In trying to understand how its done, i've read the book "Data Mining - Practical Machine Learning Tools and Techniques" which has a section on this topic but am still unsure on some primary points that are blocking my progress. Since i'm seeking guidance not solution in here, i'll tell you guys what i thinking in my head, what i think is the correct approach and in return ask for correction/guidance which will very much be appreciated. please note that i am an absolute beginner on Naïve Bayes algorithm, Data mining and in general programming so you might see stupid comments/calculations below: The training data set i'm given has 4 attributes/features that are numeric and normalized(in range[0 1]) using Weka (no missing values)and one nominal class(yes/no) 1) The data coming from a csv file is numeric HENCE * Given the attributes are numeric i use PDF (probability density function) formula. + To calculate the PDF in java i first separate the attributes based on whether they're in class yes or class no and hold them into different array (array class yes and array class no) + Then calculate the mean(sum of the values in row / number of values in that row) and standard divination for each of the 4 attributes (columns) of each class + Now to find PDF of a given value(n) i do (n-mean)^2/(2*SD^2), + Then to find P( yes | E) and P( no | E) i multiply the PDF value of all 4 given attributes and compare which is larger, which indicates the class it belongs to In temrs of Java, i'm using ArrayList of ArrayList and Double to store the attribute values. lastly i'm unsure how to to get new data? Should i ask for input file (like csv) or command prompt and ask for 4 values? I'll stop here for now (do have more questions) but I'm worried this won't get any responses given how long its got. I will really appreciate for those that give their time reading my problems and comment.

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• Get special numbers from a random number generator

  - by Wikeno

  I have a random number generator: int32_t ksp_random_table[GENERATOR_DEG] = { -1726662223, 379960547, 1735697613, 1040273694, 1313901226, 1627687941, -179304937, -2073333483, 1780058412, -1989503057, -615974602, 344556628, 939512070, -1249116260, 1507946756, -812545463, 154635395, 1388815473, -1926676823, 525320961, -1009028674, 968117788, -123449607, 1284210865, 435012392, -2017506339, -911064859, -370259173, 1132637927, 1398500161, -205601318, }; int front_pointer=3, rear_pointer=0; int32_t ksp_rand() { int32_t result; ksp_random_table[ front_pointer ] += ksp_random_table[ rear_pointer ]; result = ( ksp_random_table[ front_pointer ] >> 1 ) & 0x7fffffff; front_pointer++, rear_pointer++; if (front_pointer >= GENERATOR_DEG) front_pointer = 0; if (rear_pointer >= GENERATOR_DEG) rear_pointer = 0; return result; } void ksp_srand(unsigned int seed) { int32_t i, dst=0, kc=GENERATOR_DEG, word, hi, lo; word = ksp_random_table[0] = (seed==0) ? 1 : seed; for (i = 1; i < kc; ++i) { hi = word / 127773, lo = word % 127773; word = 16807 * lo - 2836 * hi; if (word < 0) word += 2147483647; ksp_random_table[++dst] = word; } front_pointer=3, rear_pointer=0; kc *= 10; while (--kc >= 0) ksp_rand(); } I'd like know what type of pseudo random number generation algorithm this is. My guess is a multiple linear congruential generator. And is there a way of seeding this algorithm so that after 987721(1043*947) numbers it would return 15 either even-only, odd-only or alternating odd and even numbers? It is a part of an assignment for a long term competition and i've got no idea how to solve it. I don't want the final solution, I'd like to learn how to do it myself.

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• Making pascal's triangle with mpz_t's

  - by SDLFunTimes

  Hey, I'm trying to convert a function I wrote to generate an array of longs that respresents Pascal's triangles into a function that returns an array of mpz_t's. However with the following code: mpz_t* make_triangle(int rows, int* count) { //compute triangle size using 1 + 2 + 3 + ... n = n(n + 1) / 2 *count = (rows * (rows + 1)) / 2; mpz_t* triangle = malloc((*count) * sizeof(mpz_t)); //fill in first two rows mpz_t one; mpz_init(one); mpz_set_si(one, 1); triangle[0] = one; triangle[1] = one; triangle[2] = one; int nums_to_fill = 1; int position = 3; int last_row_pos; int r, i; for(r = 3; r <= rows; r++) { //left most side triangle[position] = one; position++; //inner numbers mpz_t new_num; mpz_init(new_num); last_row_pos = ((r - 1) * (r - 2)) / 2; for(i = 0; i < nums_to_fill; i++) { mpz_add(new_num, triangle[last_row_pos + i], triangle[last_row_pos + i + 1]); triangle[position] = new_num; mpz_clear(new_num); position++; } nums_to_fill++; //right most side triangle[position] = one; position++; } return triangle; } I'm getting errors saying: incompatible types in assignment for all lines where a position in the triangle is being set (i.e.: triangle[position] = one;). Does anyone know what I might be doing wrong?

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• NullPointerException and the best way to deal with it

  - by lupin

  Note: This is homework/assignment feel not to answer if you don't want to. Ok after some search and reading these: http://stackoverflow.com/questions/425439/how-to-check-if-array-element-is-null-to-avoid-nullpointerexception-in-java http://stackoverflow.com/questions/963936/gracefully-avoiding-nullpointerexception-in-java http://c2.com/cgi/wiki?NullPointerException Am still not making any progress on how to deal with NullPointerException error on my code, snippet for questionable code: int findElement(String element) { int retval = 0; for ( int i = 0; i < setElements.length; i++) { if ( setElements[i].equals(element) ) { // This line 31 here return retval = i; } else { return retval = -1; } } return retval; } void add(String newValue) { int elem = findElement(newValue); if( numberOfElements < maxNumberOfElements && elem != -1 ) { setElements[numberOfElements] = newValue; numberOfElements++; } else { System.out.println("Element " + newValue + "already exist"); } } It compile but adding new element to a set throws a NullPointerException error. D:\javaprojects>java SetDemo Enter string element to be added A You entered A Exception in thread "main" java.lang.NullPointerException at Set.findElement(Set.java:31) at Set.add(Set.java:44) at SetDemo.main(Set.java:145) I added another check, though honestly don't have clue if this right to line 31. if ( setElements != null && setElements[i].equals(element) ) but still no joy. A documentation/tips or explanation is greatly appreciated. learning, lupin

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• Linux Kernel programming: trying to get vm_area_struct->vm_start crashes kernel

  - by confusedKid

  Hi, this is for an assignment at school, where I need to determine the size of the processes on the system using a system call. My code is as follows: ... struct task_struct *p; struct vm_area_struct *v; struct mm_struct *m; read_lock(&tasklist_lock); for_each_process(p) { printk("%ld\n", p->pid); m = p->mm; v = m->mmap; long start = v->vm_start; printk("vm_start is %ld\n", start); } read_unlock(&tasklist_lock); ... When I run a user level program that calls this system call, the output that I get is: 1 vm_start is 134512640 2 EIP: 0073:[<0806e352] CPU: 0 Not tainted ESP: 007b:0f7ecf04 EFLAGS: 00010246 Not tainted EAX: 00000000 EBX: 0fc587c0 ECX: 081fbb58 EDX: 00000000 ESI: bf88efe0 EDI: 0f482284 EBP: 0f7ecf10 DS: 007b ES: 007b 081f9bc0: [<08069ae8] show_regs+0xb4/0xb9 081f9bec: [<080587ac] segv+0x225/0x23d 081f9c8c: [<08058582] segv_handler+0x4f/0x54 081f9cac: [<08067453] sig_handler_common_skas+0xb7/0xd4 081f9cd4: [<08064748] sig_handler+0x34/0x44 081f9cec: [<080648b5] handle_signal+0x4c/0x7a 081f9d0c: [<08066227] hard_handler+0xf/0x14 081f9d1c: [<00776420] 0x776420 Kernel panic - not syncing: Kernel mode fault at addr 0x0, ip 0x806e352 EIP: 0073:[<400ea0f2] CPU: 0 Not tainted ESP: 007b:bf88ef9c EFLAGS: 00000246 Not tainted EAX: ffffffda EBX: 00000000 ECX: bf88efc8 EDX: 080483c8 ESI: 00000000 EDI: bf88efe0 EBP: bf88f038 DS: 007b ES: 007b 081f9b28: [<08069ae8] show_regs+0xb4/0xb9 081f9b54: [<08058a1a] panic_exit+0x25/0x3f 081f9b68: [<08084f54] notifier_call_chain+0x21/0x46 081f9b88: [<08084fef] __atomic_notifier_call_chain+0x17/0x19 081f9ba4: [<08085006] atomic_notifier_call_chain+0x15/0x17 081f9bc0: [<0807039a] panic+0x52/0xd8 081f9be0: [<080587ba] segv+0x233/0x23d 081f9c8c: [<08058582] segv_handler+0x4f/0x54 081f9cac: [<08067453] sig_handler_common_skas+0xb7/0xd4 081f9cd4: [<08064748] sig_handler+0x34/0x44 081f9cec: [<080648b5] handle_signal+0x4c/0x7a 081f9d0c: [<08066227] hard_handler+0xf/0x14 081f9d1c: [<00776420] 0x776420 The first process (pid = 1) gave me the vm_start without any problems, but when I try to access the second process, the kernel crashes. Can anyone tell me what's wrong, and maybe how to fix it as well? Thanks a lot! (sorry for the bad formatting....) edit: This is done in a Fedora 2.6 core in an uml environment.

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• Unexpected result in C algebra for search algorithm.

  - by Rhys

  Hi, I've implemented this search algorithm for an ordered array of integers. It works fine for the first data set I feed it (500 integers), but fails on longer searches. However, all of the sets work perfectly with the other four search algorithms I've implemented for the assignment. This is the function that returns a seg fault on line 178 (due to an unexpected negative m value). Any help would be greatly appreciated. CODE: 155 /* perform Algortihm 'InterPolationSearch' on the set 156 * and if 'key' is found in the set return it's index 157 * otherwise return -1 */ 158 int 159 interpolation_search(int *set, int len, int key) 160 { 161 int l = 0; 162 int r = len - 1; 163 int m; 164 165 while (set[l] < key && set[r] >= key) 166 { 167 168 printf ("m = l + ((key - set[l]) * (r - l)) / (set[r] - set[l])\n"); 169 170 printf ("m = %d + ((%d - %d) * (%d - %d)) / (%d - %d);\n", l, key, set[l], r, l, set[r], set[l]); 171 m = l + ((key - set[l]) * (r - l)) / (set[r] - set[l]); 172 printf ("m = %d\n", m); 173 174 #ifdef COUNT_COMPARES 175 g_compares++; 176 #endif 177 178 if (set[m] < key) 179 l = m + 1; 180 else if (set[m] > key) 181 r = m - 1; 182 else 183 return m; 184 } 185 186 if (set[l] == key) 187 return l; 188 else 189 return -1; 190 } OUTPUT: m = l + ((key - set[l]) * (r - l)) / (set[r] - set[l]) m = 0 + ((68816 - 0) * (100000 - 0)) / (114836 - 0); m = -14876 Thankyou! Rhys

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• Fastest image iteration in Python

  - by Greg

  I am creating a simple green screen app with Python 2.7.4 but am getting quite slow results. I am currently using PIL 1.1.7 to load and iterate the images and saw huge speed-ups changing from the old getpixel() to the newer load() and pixel access object indexing. However the following loop still takes around 2.5 seconds to run for an image of around 720p resolution: def colorclose(Cb_p, Cr_p, Cb_key, Cr_key, tola, tolb): temp = math.sqrt((Cb_key-Cb_p)**2+(Cr_key-Cr_p)**2) if temp < tola: return 0.0 else: if temp < tolb: return (temp-tola)/(tolb-tola) else: return 1.0 .... for x in range(width): for y in range(height): Y, cb, cr = fg_cbcr_list[x, y] mask = colorclose(cb, cr, cb_key, cr_key, tola, tolb) mask = 1 - mask bgr, bgg, bgb = bg_list[x,y] fgr, fgg, fgb = fg_list[x,y] pixels[x,y] = ( (int)(fgr - mask*key_color[0] + mask*bgr), (int)(fgg - mask*key_color[1] + mask*bgg), (int)(fgb - mask*key_color[2] + mask*bgb)) Am I doing anything hugely inefficient here which makes it run so slow? I have seen similar, simpler examples where the loop is replaced by a boolean matrix for instance, but for this case I can't see a way to replace the loop. The pixels[x,y] assignment seems to take the most amount of time but not knowing Python very well I am unsure of a more efficient way to do this. Any help would be appreciated.

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• Background image in a JFrame.

  - by thepandaatemyface

  Hi, This question has been asked a lot but everywhere the answers fall short. I can get a JFrame to display a background image just fine by extending JPanel and overriding paintComponent, like so: class BackgroundPanel extends JPanel { private ImageIcon imageIcon; public BackgroundPanel() { this.imageIcon = Icons.getIcon("foo"); } @Override protected void paintComponent(Graphics g) { super.paintComponent(g); g.drawImage(imageIcon.getImage(), 0,0,imageIcon.getIconWidth(),imageIcon.getIconHeight(),this); } } But now, how do you add a component on top of that background? When I go JFrame w = new JFrame() ; Container cp = w.getContentPane(); cp.setLayout(null); BackgroundPanel bg = new BackgroundPanel(); cp.add(bg); JPanel b = new JPanel(); b.setSize(new Dimension(30, 40)); b.setBackground(Color.red); cp.add(b); w.pack() w.setVisible(true) It shows the little red square (or any other component) and not the background, but when I remove cp.setLayout(null);, the background shows up but not my other component. I'm guessing this has something to do with the paintComponent not being called by the null LayoutManager, but I'm not at all familiar with how LayoutManagers work (this is a project for college and the assignment specifically says not to use a LayoutManager) When i make the image the background has to display null (and so, transparant (??)) the red square shows up so it might be that the background is actually above my other components) Does anyone anyone have any ideas? Thanks

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• error with "pmem.c" compiling linux source code for android

  - by Preetam

  I am compiling linux source code for android emulator. When i execute make command(for building and cross-compiling the linux source) i get the following error "pmem.c" file. root@ubuntu:~/common# make CHK include/linux/version.h CHK include/linux/utsrelease.h SYMLINK include/asm - include/asm-x86 CALL scripts/checksyscalls.sh CHK include/linux/compile.h CC drivers/misc/pmem.o drivers/misc/pmem.c:441: error: conflicting types for ‘phys_mem_access_prot’ /home/preetam/common/arch/x86/include/asm/pgtable.h:383: note: previous declaration of ‘phys_mem_access_prot’ was here drivers/misc/pmem.c: In function ‘flush_pmem_file’: drivers/misc/pmem.c:805: error: implicit declaration of function ‘dmac_flush_range’ drivers/misc/pmem.c: In function ‘pmem_setup’: drivers/misc/pmem.c:1265: error: implicit declaration of function ‘ioremap_cached’ drivers/misc/pmem.c:1266: warning: assignment makes pointer from integer without a cast make[2]: * [drivers/misc/pmem.o] Error 1 make[1]: [drivers/misc] Error 2 make: ** [drivers] Error 2 root@ubuntu:~/common# how to resolve this error. It seems that there may some problems in the "pmem.c" file and i'll have to choose different git repository. but that would be a very complex thing, as now i have already done most of the things till here. I might have to see correct version of this file. please someone tell what should i do? how to solve this errors. please help..thankyou!

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• In C# should I reuse a function / property parameter to compute temp result or create a temporary v

  - by Hamish Grubijan

  The example below may not be problematic as is, but it should be enough to illustrate a point. Imagine that there is a lot more work than trimming going on. public string Thingy { set { // I guess we can throw a null reference exception here on null. value = value.Trim(); // Well, imagine that there is so much processing to do this.thingy = value; // That this.thingy = value.Trim() would not fit on one line ... So, if the assignment has to take two lines, then I either have to abusereuse the parameter, or create a temporary variable. I am not a big fan of temporary variables. On the other hand, I am not a fan of convoluted code. I did not include an example where a function is involved, but I am sure you can imagine it. One concern I have is if a function accepted a string and the parameter was "abused", and then someone changed the signature to ref in both places - this ought to mess things up, but ... who would knowingly make such a change if it already worked without a ref? Seems like it is their responsibility in this case. If I mess with the value of value, am I doing something non-trivial under the hood? If you think that both approaches are acceptable, then which do you prefer and why? Thanks.

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• Is it a good practice to suppress warnings?

  - by Chris Cooper

  Sometimes while writing Java in Eclipse, I write code that generates warnings. A common one is this, which I get when extending the Exception class: public class NumberDivideException extends Exception { public NumberDivideException() { super("Illegal complex number operation!"); } public NumberDivideException(String s) { super(s); } } // end NumberDivideException The warning: The serializable class NumberDivideException does not declare a static final serialVersionUID field of type long. I know this warning is caused by my failure to... well, it says right above. I could solve it by including the serialVersionUID, but this is a one hour tiny assignment for school; I don't plan on serializing it anytime soon... The other option, of course, is to let Eclipse add @SuppressWarnings("serial"). But every time my mouse hovers over the Suppress option, I feel a little guilty. For programming in general, is it a good habit to suppress warnings? (Also, as a side question, is adding a "generated" serialVersionUID like serialVersionUID = -1049317663306637382L; the proper way to add a serialVersionUID, or do I have to determine the number some other way?)

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• How to obtain dependency metrics from Java source code?

  - by Bram Schoenmakers

  For an assignment we have to extract some software metrics from the Hibernate project. We have to extract the afferent coupling and efferent coupling metrics (dependency fan-in, fan-out) from each revision of each package in Hibernate. Some tools were provided which are able to extract these metrics, such as ckjm and JDepend. Other tools I have checked were Sonar, javancss and AOP. There is also the Metrics Eclipse plugin which I didn't get to work either. What these tools have in common, as far as I can see, is that they all operate on bytecode (*.class files). This is a problem, because I have to build every revision from source in order to run, say, JDepend on it. Older revisions won't build because my development stack is too recent. What I would like to do is to do this kind of analysis on source files so that I don't have to build each revision. Is this possible? Or is there a good reason why all these tools only operate on bytecode?

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• IBasic Accumulator

  - by Tara

  I am trying to do an accumulator in IBasic for a college assignment and I have the general stuff down but I cannot get it to accumulate. The code is below. My question is how do I get it to accumulate and pass to the different module. I'm trying to calculate how many right answers the user gets. Also, i need to calculate the percentage of right answers. so if the user gets 9 out of 10 right theyed answer 90% right. 'October 15, 2009 ' 'Lab 7.5 Programming Challenge 1 - Average Test Scores ' 'This is a dice game ' declare main() declare inputName(name:string) declare getAnswer(num1:int, num2:int) declare getResult(num1:int, num2:int, answer:int) declare avgRight(getRight:int) declare printInfo(name:string, getRight:int, averege:float) openconsole main() do:until inkey$<>"" closeconsole end sub main() def name:string def num1, num2, answer, total, getRight:int def averege:float inputName (name) getRight = 0 For counter = 1 to 10 getRight = getAnswer(num1, num2) getRight = getRight + 1 next counter average = avgRight (getRight) printInfo(Name, getRight, average) end sub inputName (name) Input "Please enter your name: " ,name return sub getAnswer(num1, num2) def answer, getRight:int num1 = rnd (10) + 1 num2 = rnd (10) + 1 Print num1, "+ " ,num2 Input "What is the answer to the equation? " ,answer getRight = getResult(num1, num2, answer) return getRight sub getResult(num1, num2, answer) def getRight:int if answer = num1 + num2 getRight = 1 else getRight = 0 endif return getRight sub avgRight(getRight) def average:float average = getRight / 10 return average sub printInfo(name, getRight, averege) Print "The students name is: " ,name Print "The number right is: " ,getRight Print Using ("&##.#&", "The average right is " ,averege * 100, "%") return

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• Am I deleting this properly?

  - by atch

  I have some struct: struct A { const char* name_; A* left_; A* right_; A(const char* name):name_(name), left_(nullptr), right_(nullptr){} A(const A&); //A(const A*);//ToDo A& operator=(const A&); ~A() { /*ToDo*/ }; }; /*Just to compile*/ A& A::operator=(const A& pattern) { //check for self-assignment if (this != &pattern) { void* p = new char[sizeof(A)]; } return *this; } A::A(const A& pat) { void* p = new char[sizeof(A)]; A* tmp = new (p) A("tmp"); tmp->~A(); delete tmp;//I WONDER IF HERE I SHOULD USE DIFFERENT delete[]? } int _tmain(int argc, _TCHAR* argv[]) { A a("a"); A b = a; cin.get(); return 0; } Guys I know this is far from ideal and far from finished. But please don't tell me the answer how to do it properly. I'm trying to figure it out myself. The only think I would like to know if I'm deleting my memory in proper way. Thanks.

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• Fetch request error: no entity? Probably easy, but help!

  - by cksubs

  Hi, I'm going through the Stanford iPhone course. I'm on the second Paparazzi assignment. I'm getting this error: * Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'executeFetchRequest:error: A fetch request must have an entity.' I've copied a lot of the code from this walkthrough site. Running his source code works perfectly, and at this point my code is pretty much exactly the same as his. But it throws that error. See below for the relavent bits: // Create FetchRequest NSFetchRequest *request = [[NSFetchRequest alloc] init]; NSEntityDescription *entity = [NSEntityDescription entityForName:@"Person" inManagedObjectContext:context]; [request setEntity:entity]; // Set the sort descriptor NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"personName" ascending:NO]; NSArray *sortDescriptors = [[NSArray alloc] initWithObjects:sortDescriptor, nil]; [request setSortDescriptors:sortDescriptors]; [sortDescriptors release]; [sortDescriptor release]; // set up NSFetchedResultsController to hold the fetch NSFetchedResultsController *frc = [[NSFetchedResultsController alloc] initWithFetchRequest:request managedObjectContext:context sectionNameKeyPath:nil cacheName:@"personCache"]; // execute the fetch NSError *error; NSLog(@"Prints Here"); [frc performFetch:&error]; NSLog(@"Doesn't Print Here"); I'm clearly setting the entity with [request setEntity:entity]. So the error has me stumped. Is there something I'm missing? Maybe in another file? I don't know. I'm still so confused with Objective-C.... Thanks.

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• Powershell / .Net: Get a reference to an object returned by a method

  - by Dan Menes

  I am teaching myself PowerShell by writing a simple parser. I use the .Net framework class Collections.Stack. I want to modify the object at the top of the stack in place. I know I can pop() the object off, modify it, and then push() it back on, but that strikes me as inelegant. First, I tried this: $stk = new-object Collections.Stack $stk.push( (,'My first value') ) ( $stk.peek() ) += ,'| My second value' Which threw an error: Assignment failed because [System.Collections.Stack] doesn't contain a settable property 'peek()'. At C:\Development\StackOverflow\PowerShell-Stacks\test.ps1:3 char:12 + ( $stk.peek <<<< () ) += ,'| My second value' + CategoryInfo : InvalidOperation: (peek:String) [], RuntimeException + FullyQualifiedErrorId : ParameterizedPropertyAssignmentFailed Next I tried this: $ary = $stk.peek() $ary += ,'| My second value' write-host "Array is: $ary" write-host "Stack top is: $($stk.peek())" Which prevented the error but still didn't do the right thing: Array is: My first value | My second value Stack top is: My first value Clearly, what is getting assigned to $ary is a copy of the object at the top of the stack, so when I the object in $ary, the object at the top of the stack remains unchanged. Finally, I read up on teh [ref] type, and tried this: $ary_ref = [ref]$stk.peek() $ary_ref.value += ,'| My second value' write-host "Referenced array is: $($ary_ref.value)" write-host "Stack top is still: $($stk.peek())" But still no dice: Referenced array is: My first value | My second value Stack top is still: My first value I assume the peek() method returns a reference to the actual object, not the clone. If so, then the reference appears to be being replaced by a clone by PowerShell's expression processing logic. Can somebody tell me if there is a way to do what I want to do? Or do I have to revert to pop() / modify / push()?

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• Assigning static final int in a JUnit (4.8.1) test suite

  - by Dr. Monkey

  I have a JUnit test class in which I have several static final ints that can be redefined at the top of the tester code to allow some variation in the test values. I have logic in my @BeforeClass method to ensure that the developer has entered values that won't break my tests. I would like to improve variation further by allowing these ints to be set to (sensible) random values in the @BeforeClass method if the developer sets a boolean useRandomValues = true;. I could simply remove the final keyword to allow the random values to overwrite the initialisation values, but I have final there to ensure that these values are not inadvertently changed, as some tests rely on the consistency of these values. Can I use a constructor in a JUnit test class? Eclipse starts putting red underlines everywhere if I try to make my @BeforeClass into a constructor for the test class, and making a separate constructor doesn't seem to allow assignment to these variables (even if I leave them unassigned at their declaration); Is there another way to ensure that any attempt to change these variables after the @BeforeClass method will result in a compile-time error? Can I make something final after it has been initialised?

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• Beginner problems with references to arrays in python 3.1.1

  - by Protean

  As part of the last assignment in a beginner python programing class, I have been assigned a traveling sales man problem. I settled on a recursive function to find each permutation and the sum of the distances between the destinations, however, I am have a lot of problems with references. Arrays in different instances of the Permute and Main functions of TSP seem to be pointing to the same reference. from math import sqrt class TSP: def __init__(self): self.CartisianCoordinates = [['A',[1,1]], ['B',[2,2]], ['C',[2,1]], ['D',[1,2]], ['E',[3,3]]] self.Array = [] self.Max = 0 self.StoredList = ['',0] def Distance(self, i1, i2): x1 = self.CartisianCoordinates[i1][1][0] y1 = self.CartisianCoordinates[i1][1][1] x2 = self.CartisianCoordinates[i2][1][0] y2 = self.CartisianCoordinates[i2][1][1] return sqrt(pow((x2 - x1), 2) + pow((y2 - y1), 2)) def Evaluate(self): temparray = [] Data = [] for i in range(len(self.CartisianCoordinates)): Data.append([]) for i1 in range(len(self.CartisianCoordinates)): for i2 in range(len(self.CartisianCoordinates)): if i1 != i2: temparray.append(self.Distance(i1, i2)) else: temparray.append('X') Data[i1] = temparray temparray = [] self.Array = Data self.Max = len(Data) def Permute(self,varray,index,vcarry,mcarry): #Problem Class array = varray[:] carry = vcarry[:] for i in range(self.Max): print ('ARRAY:', array) print (index,i,carry,array[index][i]) if array[index][i] != 'X': carry[0] += self.CartisianCoordinates[i][0] carry[1] += array[index][i] if len(carry) != self.Max: temparray = array[:] for j in range(self.Max):temparray[j][i] = 'X' index = i mcarry += self.Permute(temparray,index,carry,mcarry) else: return mcarry print ('pass',mcarry) return mcarry def Main(self): out = [] self.Evaluate() for i in range(self.Max): array = self.Array[:] #array appears to maintain the same reference after each copy, resulting in an incorrect array being passed to Permute after the first iteration. print (self.Array[:]) for j in range(self.Max):array[j][i] = 'X' print('I:', i, array) out.append(self.Permute(array,i,[str(self.CartisianCoordinates[i][0]),0],[])) return out SalesPerson = TSP() print(SalesPerson.Main()) It would be greatly appreciated if you could provide me with help in solving the reference problems I am having. Thank you.

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• How do I 'addChild' an DisplayObject3d from another class? (Papervision3d)

  - by Sandor

  Hi All Im kind of new in the whole papervision scene. For a school assignment I'm making a panorama version of my own room using a cube with 6 pictures in it. It created the panorama, it works great. But now I want to add clickable objects in it. One of the requirements is that my code is OOP focused. So that's what I am trying right now. Currently I got two classes - Main.as (Here i make the panorama cube as the room) - photoWall.as (Here I want to create my first clickable object) Now my problem is: I want to addChild a clickable object from photoWall.as to my panorama room. But he doesn't show it? I think it has something to do with the scenes. I use a new scene in Main.as and in photoWall.as. No errors or warnings are reported This is the piece in photoWall.as were I want to addChild my object (photoList): private function portret():void { //defining my material for the clickable portret var material : BitmapFileMaterial = new BitmapFileMaterial('images/room.jpg'); var material_list : MaterialsList = new MaterialsList( { front: material, back: material } ); // I don't know if this is nessecary? that's my problem scene = new Scene3D(); material.interactive = true; // make the clickable object as a cube var photoList : DisplayObject3D = new Cube(material_list, 1400, 1400, 1750, 1, 4, 4, 4); // positioning photoList.x = -1400; photoList.y = -280; photoList.z = 5000; //mouse event photoList.addEventListener( InteractiveScene3DEvent.OBJECT_CLICK, onPress); // this is my problem! I cannot see 'photoList' within my scene!!! scene.addChild(photoList); // trace works, so the function must be loaded. trace('function loaded'); } Hope you guys can help me out here. Would really be great! Thanks, Sandor

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• Entity Framework Update Error in ASP.NET Mvc with related entity

  - by Barry

  I have run into a problem which have searched and tried everything i can to find a solution but to no avail. I am using the same repository and context throughout the process I have a booking entity and a userExtension Entity Below is my image i then get my form collection back from my page and create a new booking public ActionResult Create(FormCollection collection) { Booking toBooking = new Booking(); i then do some validation and property assignment and find an associated BidInstance toBooking.BidInstance = bid; i have checked and the bid is not null. finally i get the user extension file from the Current IPRINCIPAL USER as below UserExtension loggedInUser = m_BookingRepository.GetBookingCurrentUser(User); toBooking.UserExtension = loggedInUser; The Code to do the getUserExtension is : public UserExtension GetBookingCurrentUser(IPrincipal currentUser) { var user = (from u in Context.aspnet_Users .Include("UserExtension") where u.UserName == currentUser.Identity.Name select u).FirstOrDefault(); if (user != null) { var userextension = (from u in Context.UserExtension.Include("aspnet_Users") where u.aspnet_Users.UserId == user.UserId select u).FirstOrDefault(); return userextension; } else{ return null; } } It returns the userextension fine and assigns it fine. i originally used the aspnet_users but encountered this problem so tried to change it to the extension entity. as soon as i call the : Context.AddToBooking(booking); Context.SaveChanges(); i get the following exception and im completely baffled by how to fix it Entities in 'FutureFlyersEntityModel.Booking' participate in the 'FK_Booking_UserExtension' relationship. 0 related 'UserExtension' were found. 1 'UserExtension' is expected. then the final error that comes to the front end is: Metadata information for the relationship 'FutureFlyersModel.FK_Booking_BidInstance' could not be retrieved. Make sure that the EdmRelationshipAttribute for the relationship has been defined in the assembly. Parameter name: relationshipName.. But both the related entities are set in the booking entity passed thruogh PLEASE HELP Im at wits end with this

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• Scheme Infix to Postfix

  - by Cody

  Let me establish that this is part of a class assignment, so I'm definitely not looking for a complete code answer. Essentially we need to write a converter in Scheme that takes a list representing a mathematical equation in infix format and then output a list with the equation in postfix format. We've been provided with the algorithm to do so, simple enough. The issue is that there is a restriction against using any of the available imperative language features. I can't figure out how to do this in a purely functional manner. This is our fist introduction to functional programming in my program. I know I'm going to be using recursion to iterate over the list of items in the infix expression like such. (define (itp ifExpr) ( ; do some processing using cond statement (itp (cdr ifExpr)) )) I have all of the processing implemented (at least as best I can without knowing how to do the rest) but the algorithm I'm using to implement this requires that operators be pushed onto a stack and used later. My question is how do I implement a stack in this function that is available to all of the recursive calls as well?

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• Get "term is undefined” error when trying to assign arrayList to List component dataSource

  - by user1814467

  I'm creating an online game where people log in and then have the list of current players displayed. When the user enters a "room" it dispatches an SFSEvent which includes a Room object with the list of users as User objects in that room. As that event's callback function, I get the list of current users which is an Array, switch the View Stack child index, and then I wrap the user list array in an ArrayList before I assign it to the MXML Spark List component's dataSource. Here's my code: My Actionscript Code Section (PreGame.as): private function onRoomJoin(event:SFSEvent):void { const room:Room = this._sfs.getRoomByName(PREGAME_ROOM); this.selectedChild = waitingRoom; /** I know I should be using event listeners * but this is a temporary fix, otherwise * I keep getting null object errors * do to the li_users list not being * created in time for the dataProvider assignment **/ setTimeout(function ():void { const userList:ArrayList = new ArrayList(room.userList); this.li_users.dataProvider = userList; // This is where the error gets thrown },1000); } My MXML Code: <?xml version="1.0" encoding="utf-8"?> <mx:ViewStack xmlns:fx="http://ns.adobe.com/mxml/2009" xmlns:s="library://ns.adobe.com/flex/spark" xmlns:mx="library://ns.adobe.com/flex/mx" initialize="preGame_initializeHandler(event)" > <fx:Script source="PreGame.as"/> <s:NavigatorContent id="nc_loginScreen"> /** Login Screen Code **/ </s:NavigatorContent> /** Start of Waiting Room code **/ <s:NavigatorContent id="waitingRoom"> <s:Panel id="pn_users" width="400" height="400" title="Users"> /** This is the List in question **/ <s:List id="li_users" width="100%" height="100%"/> </s:Panel> </s:NavigatorContent> </mx:ViewStack> However, I keep getting this error: TypeError: Error #1010: A term is undefined and has no properties Any ideas what I'm doing wrong? The arrayList has data, so I know it's not empty/null.

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• What is happening in this T-SQL code?

  - by Ben McCormack

  I'm just starting to learn T-SQL and could use some help in understanding what's going on in a particular block of code. I modified some code in an answer I received in a previous question, and here is the code in question: DECLARE @column_list AS varchar(max) SELECT @column_list = COALESCE(@column_list, ',') + 'SUM(Case When Sku2=' + CONVERT(varchar, Sku2) + ' Then Quantity Else 0 End) As [' + CONVERT(varchar, Sku2) + ' - ' + Convert(varchar,Description) +'],' FROM OrderDetailDeliveryReview Inner Join InvMast on SKU2 = SKU and LocationTypeID=4 GROUP BY Sku2 , Description ORDER BY Sku2 Set @column_list = Left(@column_list,Len(@column_list)-1) Select @column_list ---------------------------------------- 1 row is returned: ,SUM(Case When Sku2=157 Then Quantity Else 0 End) As [157 -..., SUM(Case ... The T-SQL code does exactly what I want, which is to make a single result based on the results of a query, which will then be used in another query. However, I can't figure out how the SELECT @column_list =... statement is putting multiple values into a single string of characters by being inside a SELECT statement. Without the assignment to @column_list, the SELECT statement would simply return multiple rows. How is it that by having the variable within the SELECT statement that the results get "flattened" down into one value? How should I read this T-SQL to properly understand what's going on?

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• #indent "off" in F#

  - by anta40

  I just started learning F#, and tried a code from the wiki: I prefer tabs to spaces, so I change the code a bit into this: #indent "off" open System open System.Windows.Forms let form = new Form(Visible=true, TopMost=true, Text="Welcome to F#") let label = let temp = new Label() let x = 3 + (4 * 5) temp.Text <- sprintf "x = %d" x temp form.Controls.Add(label) [<STAThread>] Application.Run(form) The output is: Microsoft (R) F# 2.0 Compiler build 4.0.30319.1 Copyright (c) Microsoft Corporation. All Rights Reserved. fstest2.fs(1,1): warning FS0062: This construct is for ML compatibility. Conside r using a file with extension '.ml' or '.mli' instead. You can disable this warn ing by using '--mlcompatibility' or '--nowarn:62'. fstest2.fs(9,2): error FS0010: Unexpected keyword 'let' or 'use' in expression. Expected 'in' or other token. fstest2.fs(13,1): error FS0597: Successive arguments should be separated by spac es or tupled, and arguments involving function or method applications should be parenthesized fstest2.fs(9,14): error FS0374: Invalid expression on left of assignment fstest2.fs(16,1): error FS0010: Unexpected identifier in definition Guess the error is somewhere in the let label block, but couldn't figure it out.

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• What ever happened to APL?

  - by lkessler

  When I was at University 30 years ago, I used a programming language called APL. I believe the acronym stood for "A Programming Language", This language was interpretive and was especially useful for array and matrix operations with powerful operators and library functions to help with that. Did you use APL? Is this language still in use anywhere? Is it still available, either commercially or open source? I remember the combinatorics assignment we had. It was complex. It took a week of work for people to program it in PL/1 and those programs ranged from 500 to 1000 lines long. I wrote it in APL in under an hour. I left it at 10 lines for readability, although I should have been a purist and worked another hour to get it into 1 line. The PL/1 programs took 1 or 2 minutes to run on the IBM mainframe and solve the problem. The computer charge was $20. My APL program took 2 hours to run and the charge was $1,500 which was paid for by our Computer Science Department's budget. That's when I realized that a week of my time is worth way more than saving some $'s in someone else's budget. I got an A+ in the course. p.s. Don't miss this presentation entitled: "APL one of the greatest programming languages ever"

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