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  • Python OOP and lists

    - by Mikk
    Hi, I'm new to Python and it's OOP stuff and can't get it to work. Here's my code: class Tree: root = None; data = []; def __init__(self, equation): self.root = equation; def appendLeft(self, data): self.data.insert(0, data); def appendRight(self, data): self.data.append(data); def calculateLeft(self): result = []; for item in (self.getLeft()): if (type(item) == type(self)): data = item.calculateLeft(); else: data = item; result.append(item); return result; def getLeft(self): return self.data; def getRight(self): data = self.data; data.reverse(); return data; tree2 = Tree("*"); tree2.appendRight(44); tree2.appendLeft(20); tree = Tree("+"); tree.appendRight(4); tree.appendLeft(10); tree.appendLeft(tree2); print(tree.calculateLeft()); It looks like tree2 and tree are sharing list "data"? At the moment I'd like it to output something like [[20,44], 10, 4], but when I tree.appendLeft(tree2) I get RuntimeError: maximum recursion depth exceeded, and when i even won't appendLeft(tree2) it outputs [10, 20, 44, 4] (!!!). What am I missing here? I'm using Portable Python 3.0.1. Thank you

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  • Java: how to access assignments in try-catch -loop?

    - by HH
    $ javac TestInit2.java TestInit2.java:13: variable unknown might not have been initialized System.out.println(unknown); ^ 1 error Code import java.util.*; import java.io.*; public class TestInit2 { public static void main(String[] args){ String unknown; try{ unknown="cannot see me, why?"; }catch(Exception e){ e.printStackTrace(); } System.out.println(unknown); } }

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  • what is the point of escaping quotation marks in php

    - by Jacksta
    Here is a validation script from a book I am learning, Why is escaping the quotation marks necassery? e.g. <option value=\"char\">char</option> <?php //validate important input if ((!$_POST[table_name]) || (!$_POST[num_fields])) { header( "location: show_createtable.html"); exit; } //begin creating form for display $form_block = " <form action=\"do_createtable.php\" method=\"post\"> <input name=\"table_name\" type=\"hidden\" value=\"$_POST[table_name]\"> <table cellspacing=\"5\" cellpadding=\"5\"> <tr> <th>Field Name</th><th>Field Type</th><th>Table Length</th> </tr>"; //count from 0 until you reach the number fo fields for ($i = 0; $i <$_POST[num_fields]; $i++) { $form_block .=" <tr> <td align=center><input type=\"texr\" name=\"field name[]\" size=\"30\"></td> <td align=center> <select name=\"field_type[]\"> <option value=\"char\">char</option> <option value=\"date\">date</option> <option value=\"float\">float</option> <option value=\"int\">int</option> <option value=\"text\">text</option> <option value=\"varchar\">varchar</option> </select> </td> <td align=center><input type=\"text\" name=\"field_length[]\" size=\"5\"> </td> </tr>"; } //finish up the form $form_block .= " <tr> <td align=center colspan=3><input type =\"submit\" value=\"create table\"> </td> </tr> </table> </form>"; ?> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <title>Create a database table: Step 2</title> </head> <body> <h1>defnie fields for <? echo "$_POST[table_name]"; ?> </h1> <? echo "$form_block"; ?> </body> </html>

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  • Type hinting in Python

    - by pingvinus
    I'm studying Python after a lot of PHP experience and it would be handy to have type-hinting in Python. Looks like eclipse + pydev doesn't support this. Any suggestions? For example, I want my IDE to show function docstrings and types, when I use it, like: def f(x: int) -> int: r"""Adds 3 to x""" return x + 3 f( #and now IDE shows everything about types

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  • Can someone explain me implicit conversions in Scala?

    - by Oscar Reyes
    And more specifically how does the BigInt works for convert int to BigInt? In the source code it reads: ... implicit def int2bigInt(i: Int): BigInt = apply(i) ... How is this code invoked? I can understand how this other sample: "Date literals" works. In. val christmas = 24 Dec 2010 Defined by: implicit def dateLiterals(date: Int) = new { import java.util.Date def Dec(year: Int) = new Date(year, 11, date) } When int get's passed the message Dec with an int as parameter, the system looks for another method that can handle the request, in this case Dec(year:Int) Q1. Am I right in my understanding of Date literals? Q2. How does it apply to BigInt? Thanks

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  • side effect gotchas in python/numpy? horror stories and narrow escapes wanted

    - by shabbychef
    I am considering moving from Matlab to Python/numpy for data analysis and numerical simulations. I have used Matlab (and SML-NJ) for years, and am very comfortable in the functional environment without side effects (barring I/O), but am a little reluctant about the side effects in Python. Can people share their favorite gotchas regarding side effects, and if possible, how they got around them? As an example, I was a bit surprised when I tried the following code in Python: lofls = [[]] * 4 #an accident waiting to happen! lofls[0].append(7) #not what I was expecting... print lofls #gives [[7], [7], [7], [7]] #instead, I should have done this (I think) lofls = [[] for x in range(4)] lofls[0].append(7) #only appends to the first list print lofls #gives [[7], [], [], []] thanks in advance

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  • Read Response.write in another Page

    - by Sri Kumar
    Hello All, I have a page www.senderdomain.com/sender.aspx, from which i need to write a string to another page in other domain www.receiverdomain.com/receiver.aspx In sender.aspx i have written Response.Write("Hello"); Response.Redirect(Request.UrlReferrer.ToString()); It gets redirected to respective receiver.aspx page, but I am not sure how to get the text "Hello" in receiver.aspx page. Can any pl help on this?

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  • How to parse XML file to get specific data effectively

    - by Carlos_Liu
    I have an XML file looks like this: <?xml version="1.0" encoding="utf-8" ?> <PathMasks> <Mask desc="Masks_X1"> <config id="01" mask="88" /> <config id="03" mask="80" /> <config id="51" mask="85" /> </Mask> <Mask desc="Masks_X2"> <config id="70" mask="1" /> <config id="73" mask="6" /> </Mask> <Types> <path id="01" desc="TC->PP1" /> <path id="02" desc="TC->PP2" /> <path id="03" desc="TC->PPn" /> </Types> </PathMasks> How to parse the file and get all the data of Mask_X1 as following: id value ===== 01, 88 03, 80 51, 85

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  • Strengths and weaknesses of JIT compilers for Python

    - by Az
    Hi there, I'm currently aware of the following Python JIT compilers: Psyco, PyPy and Unladen Swallow. Basically, I'd like to ask for your personal experiences on the strengths and weaknesses of these compilers - and if there are any others worth looking into. Thanks in advance, Az

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  • Numerating Comments

    - by John
    The code below prints out all comments for a given "submissionid" in chronological order. How could I numerate these comments? (In other words, how do I print out a "1." next to the oldest comment, a "2." next to the second-oldest comment, etc.?) $submission = mysql_real_escape_string($_GET['submission']); $submissionid = mysql_real_escape_string($_GET['submissionid']); $sqlStr = "SELECT comment.comment, comment.datecommented, login.username FROM comment LEFT JOIN login ON comment.loginid=login.loginid WHERE submissionid=$submissionid ORDER BY comment.datecommented ASC LIMIT 100"; $result = mysql_query($sqlStr); $arr = array(); echo "<table class=\"commentecho\">"; while ($row = mysql_fetch_array($result)) { echo '<tr>'; echo '<td class="commentname1">'.stripslashes($row["comment"]).'</td>'; echo '</tr>'; echo '<tr>'; echo '<td class="commentname2"><a href="http://www...com/sandbox/members/index.php?profile='.$row["username"].'">'.$row["username"].'</a>'.date('l, F j, Y &\nb\sp &\nb\sp g:i a &\nb\sp &\nb\sp \N\E\W &\nb\sp \Y\O\R\K &\nb\sp \T\I\M\E', strtotime($row["datecommented"])).'</td>'; echo '</tr>'; } echo "</table>"

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  • Why is my simple recusive method's final return value always off by 1?

    - by FrankTheTank
    I'm attempting to create a text-based version of this game: http://www.cse.nd.edu/java/SameGame.html Here is the code I have so far: #include <iostream> #include <vector> #include <ctime> class Clickomania { public: Clickomania(); std::vector<std::vector<int> > board; int move(int, int); bool isSolved(); void print(); void pushDown(); bool isValid(); }; Clickomania::Clickomania() : board(12, std::vector<int>(8,0)) { srand((unsigned)time(0)); for(int i = 0; i < 12; i++) { for(int j = 0; j < 8; j++) { int color = (rand() % 3) + 1; board[i][j] = color; } } } void Clickomania::pushDown() { for(int i = 0; i < 8; i++) { for(int j = 0; j < 12; j++) { if (board[j][i] == 0) { for(int k = j; k > 0; k--) { board[k][i] = board[k-1][i]; } board[0][i] = 0; } } } } int Clickomania::move(int row, int col) { bool match = false; int totalMatches = 0; if (row > 12 || row < 0 || col > 8 || col < 0) { return 0; } int currentColor = board[row][col]; board[row][col] = 0; if ((row + 1) < 12) { if (board[row+1][col] == currentColor) { match = true; totalMatches++; totalMatches += move(row+1, col); } } if ((row - 1) >= 0) { if (board[row-1][col] == currentColor) { match = true; totalMatches++; totalMatches += move(row-1, col); } } if ((col + 1) < 8) { if (board[row][col+1] == currentColor) { match = true; totalMatches++; totalMatches += move(row, col+1); } } if ((col - 1) >= 0) { if (board[row][col-1] == currentColor) { match = true; totalMatches++; totalMatches += move(row, col-1); } } return totalMatches; } void Clickomania::print() { for(int i = 0; i < 12; i++) { for(int j = 0; j < 8; j++) { std::cout << board[i][j]; } std::cout << "\n"; } } int main() { Clickomania game; game.print(); int row; int col; std::cout << "Enter row: "; std::cin >> row; std::cout << "Enter col: "; std::cin >> col; int numDestroyed = game.move(row,col); game.print(); std::cout << "Destroyed: " << numDestroyed << "\n"; } The method that is giving me trouble is my "move" method. This method, given a pair of coordinates, should delete all the squares at that coordinate with the same number and likewise with all the squares with the same number connected to it. If you play the link I gave above you'll see how the deletion works on a click. int Clickomania::move(int row, int col) { bool match = false; int totalMatches = 0; if (row > 12 || row < 0 || col > 8 || col < 0) { return 0; } int currentColor = board[row][col]; board[row][col] = 0; if ((row + 1) < 12) { if (board[row+1][col] == currentColor) { match = true; totalMatches++; totalMatches += move(row+1, col); } } if ((row - 1) >= 0) { if (board[row-1][col] == currentColor) { match = true; totalMatches++; totalMatches += move(row-1, col); } } if ((col + 1) < 8) { if (board[row][col+1] == currentColor) { match = true; totalMatches++; totalMatches += move(row, col+1); } } if ((col - 1) >= 0) { if (board[row][col-1] == currentColor) { match = true; totalMatches++; totalMatches += move(row, col-1); } } return totalMatches; } My move() method above works fine, as in, it will delete the appropriate "blocks" and replace them with zeros. However, the number of destroyed (value returned) is always one off (too small). I believe this is because the first call of move() isn't being counted but I don't know how to differentiate between the first call or subsequent calls in that recursive method. How can I modify my move() method so it returns the correct number of destroyed blocks?

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  • Strange Bubble sort behaviour.

    - by user271528
    Can anyone explain why this bubble sort function doesn't work and why I loose number in my output. I'm very new to C, so please forgive me if this is something very obvious I have missed. #include <stdio.h> #include int bubble(int array[],int length) { int i, j; int temp; for(i = 0; i < (length); ++i) { for(j = 0; j < (length - 1); ++j) { if(array[i] array[i+1]) { temp = array[i+1]; array[i+1] = array[i]; array[i] = temp; } } } return 0; } int main() { int array[] = {12,234,3452,5643,0}; int i; int length; length = (sizeof(array)/sizeof(int)); printf("Size of array = %d\n", length); bubble(array, length); for (i = 0; i < (length); ++i) { printf("%d\n", array[i]); } return 0; } Output Size of array = 5 12 234 3452 0 0

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  • How to learn flex?

    - by Zenzen
    So I'm starting an internship as a Flex developer in ~2weeks thanks to a friend of mine. The thing is I know squat about Flex - it is an internship after all so I'm supposed to learn there, but nonetheless I want to have some basic understanding of Flex before I start (eventually I want to become a JEE/Flex dev). So my question is simple, which book(s) would you recommend me to start with? Are there any "must have" books, like let's say "Thinking in C++" for C++ etc.? I already heard about a few video tutorials and I will surely check them out but I'd also want to get some decent books.

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  • whats the diference between train, validation and test set, in neural networks?

    - by Daniel
    Im using this library http://pastebin.com/raw.php?i=aMtVv4RZ to implement a learning agent. I have generated the train cases, but i dont know for sure what are the validation and test sets, the teacher says: 70% should be train cases, 10% will be test cases and the rest 20% should be validation cases. Thanks. edit i have this code, for training.. but i have no ideia when to stop training.. def train(self, train, validation, N=0.3, M=0.1): # N: learning rate # M: momentum factor accuracy = list() while(True): error = 0.0 for p in train: input, target = p self.update(input) error = error + self.backPropagate(target, N, M) print "validation" total = 0 for p in validation: input, target = p output = self.update(input) total += sum([abs(target - output) for target, output in zip(target, output)]) #calculates sum of absolute diference between target and output accuracy.append(total) print min(accuracy) print sum(accuracy[-5:])/5 #if i % 100 == 0: print 'error %-14f' % error if ? < ?: break

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  • Guaranteed COM object release?

    - by Jurily
    I wrote the following code under the assumption that Excel will die with Monkey: class ExcelMonkey { private static Excel.Application xl = new Excel.Application(); public static bool parse(string filename) { if (filename.Contains("foo")) { var workbook = xl.Workbooks.Open(filename); var sheet = workbook.Worksheets.get_Item(1); // do stuff return true; } return false; } } How do I make sure it does? Do I need to release workbook and sheet separately? I want to have Excel around for the lifetime of the program, it's a huge performance improvement.

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  • How to draw a circle in java with a radius and points around the edge

    - by windopal
    Hi, I'm really stuck on how to go about programming this. I need to draw a circle within a JFrame with a radius and points around the circumference. i can mathematically calculate how to find the coordinates of the point around the edge but i cant seem to be able to program the circle. I am currently using a Ellipse2D method but that doesn't seem to work and doesn't return a radius, as under my understanding, it doesn't draw the circle from the center rather from a starting coordinate using a height and width. My current code is on a separate frame but i need to add it to my existing frame. import java.awt.*; import javax.swing.*; import java.awt.geom.*; public class circle extends JFrame { public circle() { super("circle"); setSize(410, 435); setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); Panel sp = new Panel(); Container content = getContentPane(); content.add(sp); setContentPane(content); setVisible(true); } public static void main (String args[]){ circle sign = new circle(); } } class Panel extends JPanel { public void paintComponent(Graphics comp) { super.paintComponent(comp); Graphics2D comp2D = (Graphics2D) comp; comp2D.setColor(Color.red); Ellipse2D.Float sign1 = new Ellipse2D.Float(0F, 0F, 350F, 350F); comp2D.fill(sign1); } }

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  • Python filter/remove URLs from a list

    - by Eef
    Hi. I have a text file of URLs, about 14000. Below is a couple of examples: http://www.domainname.com/pagename?CONTENT_ITEM_ID=100&param2=123 http://www.domainname.com/images?IMAGE_ID=10 http://www.domainname.com/pagename?CONTENT_ITEM_ID=101&param2=123 http://www.domainname.com/images?IMAGE_ID=11 http://www.domainname.com/pagename?CONTENT_ITEM_ID=102&param2=123 I have loaded the text file into a Python list and I am trying to get all the URLs with CONTENT_ITEM_ID separated off into a list of their own. What would be the best way to do this in Python? Cheers

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