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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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  • VB.net Cross-Thread

    - by PandaNL
    Hello, I have a cmd command that needs to be executed, when the command starts it starts to fill a progressbar. When the cmd command is done the progressbar needs to fill up to 100. This is the code i use, but it gives me an error when the progressbar.Value = 100 comes up. Public Class Form1 Dim teller As Integer Private Sub Timer1_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles TimerProgressbar.Tick teller += 1 ProgressBar1.Value = teller If ProgressBar1.Value = ProgressBar1.Maximum Then TimerProgressbar.Stop() End If End Sub This are the tow commands in another private sub where the app is crashing on ProgressBar1.Value = 100 TimerProgressbar.Stop() When i debug it and i try it out it crashes on ProgressBar1.Value = 100 But when i build it under Windows 7 it runs fine without crashing, however a few people reported me it crashes on there Windows xp system. VB gives me a suggestions about Cross Thread, but i don't know how i could make it work with this.

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  • [mysql] diff between tables

    - by www.yegorov-p.ru
    I have two tables, with the same structure, for example: table "first' with columns 'a','b','c' and table 'second' with the same columns. How to find difference betweet those two tables? Of course, I can make some script on python, that will make set(a)-set(b), but I think there is some way to do it in mysql.

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  • For-loops in python

    - by Znarkus
    What is the best way of doing this in Python? for (v = n / 2 - 1; v >= 0; v--) I actually tried Google first, but as far as I can see the only solution would be to use while.

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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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  • java source code doubt

    - by abson
    this compiles class ex1 { public int show() { try { int a=10/10; return 10;} catch(ArithmeticException e) { System.out.println(e); } finally { System.out.println("Finally");} System.out.println("hello"); return 20; } } on the other hand this doesn't class ex15 { public int show() { try { int a=10/0; return 10;} catch(ArithmeticException e) { System.out.println(e); } finally { System.out.println("Finally"); return 40;} System.out.println("hello"); return 20; } } why is it so?

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  • What is ADO.NET?

    - by ChrisC
    I've written a few Access db's and used some light VBA, and had an OO class. Now I'm undertaking to write a C# db app. I've got VS and System.Data.SQLite installed and connected, and have entered my tables and columns, but that's where I'm stuck. I'm trying to find what info and tutorials I need to look for, but there are a lot of terms I don't understand and I don't know if or exactly how they apply to my project. I've read definitions for these terms (Wikipedia and elsewhere), but the definitions don't make sense to me because I don't know what they are or how they fit together or which ones are optional or not optional for my project. Some of the terms on the System.Data.SQLite website (I wanted to use System.Data.SQLite for my db). I figured my first step in my project would be to get the db and queries set up and tested. Please tell me if there are other pieces of this part of the puzzle I will need to know about, too. If I can figure out what's what, I can start looking for the tutorials I need. (btw, I know I don't want to use an ORM because my app is so simple, and because I want to keep from biting off too much too soon.) Thank you very much. SQLite.NET ADO.NET ADO.NET provider ADO.NET 2.0 Provider for SQLite SQLite Entity Framework SQLite Entity Framework provider

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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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  • Change Variable back to original value after Regex matching.

    - by Brad Johansen
    I just "finished" expanding my Palindrome Tester, made in C#. To allow for phrases I added a simple regex match for all non-alphanumeric characters. At the end of the program it states " is(n't) a palindrome." But now with the regex it prints the no spaces/punctuation version of it. I would like to be able to print the original user input. How do I do that? Here is my program: http://gist.github.com/384565

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  • How do I create a list or set object in a class in Python?

    - by Az
    For my project, the role of the Lecturer (defined as a class) is to offer projects to students. Project itself is also a class. I have some global dictionaries, keyed by the unique numeric id's for lecturers and projects that map to objects. Thus for the "lecturers" dictionary (currently): lecturer[id] = Lecturer(lec_name, lec_id, max_students) I'm currently reading in a white-space delimited text file that has been generated from a database. I have no direct access to the database so I haven't much say on how the file is formatted. Here's a fictionalised snippet that shows how the text file is structured. Please pardon the cheesiness. 0001 001 "Miyamoto, S." "Even Newer Super Mario Bros" 0002 001 "Miyamoto, S." "Legend of Zelda: Skies of Hyrule" 0003 002 "Molyneux, P." "Project Milo" 0004 002 "Molyneux, P." "Fable III" 0005 003 "Blow, J." "Ponytail" The structure of each line is basically proj_id, lec_id, lec_name, proj_name. Now, I'm currently reading the relevant data into the relevant objects. Thus, proj_id is stored in class Project whereas lec_name is a class Lecturer object, et al. The Lecturer and Project classes are not currently related. However, as I read in each line from the text file, for that line, I wish to read in the project offered by the lecturer into the Lecturer class; I'm already reading the proj_id into the Project class. I'd like to create an object in Lecturer called offered_proj which should be a set or list of the projects offered by that lecturer. Thus whenever, for a line, I read in a new project under the same lec_id, offered_proj will be updated with that project. If I wanted to get display a list of projects offered by a lecturer I'd ideally just want to use print lecturers[lec_id].offered_proj. My Python isn't great and I'd appreciate it if someone could show me a way to do that. I'm not sure if it's better as a set or a list, as well. Update After the advice from Alex Martelli and Oddthinking I went back and made some changes and tried to print the results. Here's the code snippet: for line in csv_file: proj_id = int(line[0]) lec_id = int(line[1]) lec_name = line[2] proj_name = line[3] projects[proj_id] = Project(proj_id, proj_name) lecturers[lec_id] = Lecturer(lec_id, lec_name) if lec_id in lecturers.keys(): lecturers[lec_id].offered_proj.add(proj_id) print lec_id, lecturers[lec_id].offered_proj The print lecturers[lec_id].offered_proj line prints the following output: 001 set([0001]) 001 set([0002]) 002 set([0003]) 002 set([0004]) 003 set([0005]) It basically feels like the set is being over-written or somesuch. So if I try to print for a specific lecturer print lec_id, lecturers[001].offered_proj all I get is the last the proj_id that has been read in.

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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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  • GoTo statements, and alternatives (help me please im new) (VB.net)

    - by qais
    Basically I posted a code snippet on a forum asking for help and people pointed out to me that using GoTo statements is very bad programming practise so I'm just wondering, why is it bad? And also what alternative is there to use, like for example in this program ive done for homework the user has to input their date of birth and if the month/date/year are invalid or unrealistic(using if statements checking the integer inputs size, if theres any better way to do this i'd appreciate if you could tell me that also :D) then how would i be able to loop back to ask them again? heres a little extract of my code retryday: Console.WriteLine("Please enter the day you were born : ") day = Console.ReadLine If day > 31 Or day < 1 Then Console.WriteLine("Please enter a valid day") GoTo retryday End If

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  • Does code in the constructor add to code in subclass constructors?

    - by Jeremy Rudd
    Does code in the constructor add to code in subclass constructors? Or does the subclass's constructor override the superclass? Given this example superclass constructor: class Car{ function Car(){ trace("CAR") } } ...and this subclass constructor: class FordCar extends Car{ function FordCar(){ trace("FORD") } } When an instance of FordCar is created, will this trace "Car" and "Ford" ??

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  • Java ArrayList initialization

    - by Jonathan
    I am aware that you can initialize an array during instantiation as follows: String[] names = new String[] {"Ryan", "Julie", "Bob"}; Is there a way to do the same thing with an ArrayList? Or must I add the contents individually with array.add()? Thanks, Jonathan

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  • Why isn't my algorithm for find the biggest and smallest inputs working?

    - by Matt Ellen
    I have started a new job, and with it comes a new language: Ironpython. Thankfully a good language :D Before starting I got to grips with Python on the whole, but that was only a week's worth of learning. Now I'm writing actual code. I've been charged with writing an algorithm that finds the best input parameter to collect data with. The basic algorithm is (as I've been instructed): Set the input parameter to a good guess Start collecting data When data is available stop collecting find the highest point If the point before this (i.e. for the previous parameter value) was higher and the point before that was lower then we've found the max otherwise the input parameter is increased by the initial guess. goto 2 If the max is found then the min needs to be found. To do this the algorithm carries on increasing the input, but by 1/10 of the max, until the current point is greater than the previous point and the point before that is also greater. Once the min is found then the algorithm stops. Currently I have a simplified data generator outputting the sin of the input, so that I know that the min value should be PI and the max value should be PI/2 The main Python code looks like this (don't worry, this is just for my edification, I don't write real code like this): import sys sys.path.append(r"F:\Programming Source\C#\PythonHelp\PythonHelp\bin\Debug") import clr clr.AddReferenceToFile("PythonHelpClasses.dll") import PythonHelpClasses from PHCStruct import Helper from System import Math helper = Helper() def run(): b = PythonHelpClasses.Executor() a = PythonHelpClasses.HasAnEvent() b.Input = 0.0 helper.__init__() def AnEventHandler(e): b.Stop() h = helper h.lastLastVal, h.lastVal, h.currentVal = h.lastVal, h.currentVal, e.Number if h.lastLastVal < h.lastVal and h.currentVal < h.lastVal and h.NotPast90: h.NotPast90 = False h.bestInput = h.lastInput inputInc = 0.0 if h.NotPast90: inputInc = Math.PI/10.0 else: inputInc = h.bestInput/10.0 if h.lastLastVal > h.lastVal and h.currentVal > h.lastVal and h.NotPast180: h.NotPast180 = False if h.NotPast180: h.lastInput, b.Input = b.Input, b.Input + inputInc b.Start(a) else: print "Best input:", h.bestInput print "Last input:", h.lastInput b.Stop() a.AnEvent += AnEventHandler b.Start(a) PHCStruct.py: class Helper(): def __init__(self): self.currentVal = 0 self.lastVal = 0 self.lastLastVal = 0 self.NotPast90 = True self.NotPast180 = True self.bestInput = 0 self.lastInput = 0 PythonHelpClasses has two small classes I wrote in C# before I realised how to do it in Ironpython. Executor runs a delegate asynchronously while it's running member is true. The important code: public void Start(HasAnEvent hae) { running = true; RunDelegate r = new RunDelegate(hae.UpdateNumber); AsyncCallback ac = new AsyncCallback(UpdateDone); IAsyncResult ar = r.BeginInvoke(Input, ac, null); } public void Stop() { running = false; } public void UpdateDone(IAsyncResult ar) { RunDelegate r = (RunDelegate)((AsyncResult)ar).AsyncDelegate; r.EndInvoke(ar); if (running) { AsyncCallback ac = new AsyncCallback(UpdateDone); IAsyncResult ar2 = r.BeginInvoke(Input, ac, null); } } HasAnEvent has a function that generates the sin of its input and fires an event with that result as its argument. i.e.: public void UpdateNumber(double val) { AnEventArgs e = new AnEventArgs(Math.Sin(val)); System.Threading.Thread.Sleep(1000); if (null != AnEvent) { AnEvent(e); } } The sleep is in there just to slow things down a bit. The problem I am getting is that the algorithm is not coming up with the best input being PI/2 and the final input being PI, but I can't see why. Also the best and final inputs are different each time I run the programme. Can anyone see why? Also when the algorithm terminates the best and final inputs are printed to the screen multiple times, not just once. Can someone explain why?

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  • Scrapy Could not find spider Error

    - by Nacari
    I have been trying to get a simple spider to run with scrapy, but keep getting the error: Could not find spider for domain:stackexchange.com when I run the code with the expression scrapy-ctl.py crawl stackexchange.com. The spider is as follow: from scrapy.spider import BaseSpider from __future__ import absolute_import class StackExchangeSpider(BaseSpider): domain_name = "stackexchange.com" start_urls = [ "http://www.stackexchange.com/", ] def parse(self, response): filename = response.url.split("/")[-2] open(filename, 'wb').write(response.body) SPIDER = StackExchangeSpider()` Another person posted almost the exact same problem months ago but did not say how they fixed it, http://stackoverflow.com/questions/1806990/scrapy-spider-is-not-working I have been following the turtorial exactly at http://doc.scrapy.org/intro/tutorial.html, and cannot figure out why it is not working.

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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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  • Help with copy and deepcopy in Python

    - by Az
    Hi there, I think I tried to ask for far too much in my previous question so apologies for that. Let me lay out my situation in as simple a manner as I can this time. Basically, I've got a bunch of dictionaries that reference my objects, which are in turn mapped using SQLAlchemy. All fine with me. However, I want to make iterative changes to the contents of those dictionaries. The problem is that doing so will change the objects they reference---and using copy.copy() does no good since it only copies the references contained within the dictionary. Thus even if copied something, when I try to, say print the contents of the dictionary, I'll only get the latest updated values for the object. This is why I wanted to use copy.deepcopy() but that does not work with SQLAlchemy. Now I'm in a dilemma since I need to copy certain attributes of my object before making said iterative changes. In summary, I need to use SQLAlchemy and at the same time make sure I can have a copy of my object attributes when making changes so I don't change the referenced object itself. Any advice, help, suggestions, etc.?

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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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