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  • Length-1 arrays can be converted to python scalars error? python

    - by Randy
    from numpy import * from pylab import * from math import * def LogisticMap(a,x): return 4.*a*x*(1.-x) def CosineMap(a,x): return a*cos(x/(2.*pi)) def TentMap(a,x): if x>= 0 or x<0.5: return 2.*a*x if x>=0.5 or x<=1.: return 2.*a*(1.-x) a = 0.98 N = 40 xaxis = arange(0.0,N,1.0) Func = CosineMap subplot(211) title(str(Func.func_name) + ' at a=%g and its second iterate' %a) ylabel('X(n+1)') # set y-axis label plot(xaxis,Func(a,xaxis), 'g', antialiased=True) subplot(212) ylabel('X(n+1)') # set y-axis label xlabel('X(n)') # set x-axis label plot(xaxis,Func(a,Func(a,xaxis)), 'bo', antialiased=True) My program is supposed to take any of the three defined functions and plot it. They all take in a value x from the array xaxis from 0 to N and then return the value. I want it to plot a graph of xaxis vs f(xaxis) with f being any of the three above functions. The logisticmap function works fine, but for CosineMap i get the error "only length-1 arrays can be converted to python scalars" and for TentMap i get error "The truth value of an array with more than one element is ambiguous, use a.any() or a.all()". My tent map function is suppose to return 2*a*x if 0<=x<0.5 and it's suppose to return 2*a*(1-x) if 0.5<=0<=1.

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  • How do interpreters written in C and C++ bind identifiers to C(++) functions

    - by sub
    I'm talking about C and/or C++ here as this are the only languages I know used for interpreters where the following could be a problem: If we have an interpreted language X how can a library written for it add functions to the language which can then be called from within programs written in the language? PHP example: substr( $str, 5, 10 ); How is the function substr added to the "function pool" of PHP so it can be called from within scripts? It is easy for PHP storing all registered function names in an array and searching through it as a function is called in a script. However, as there obviously is no eval in C(++), how can the function then be called? I assume PHP doesn't have 100MB of code like: if( identifier == "substr" ) { return PHP_SUBSTR(...); } else if( ... ) { ... } Ha ha, that would be pretty funny. I hope you have understood my question so far. How do interpreters written in C/C++ solve this problem? How can I solve this for my own experimental toy interpreter written in C++?

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  • Python program to search for specific strings in hash values (coding help)

    - by Diego
    Trying to write a code that searches hash values for specific string's (input by user) and returns the hash if searchquery is present in that line. Doing this to kind of just learn python a bit more, but it could be a real world application used by an HR department to search a .csv resume database for specific words in each resume. I'd like this program to look through a .csv file that has three entries per line (id#;applicant name;resume text) I set it up so that it creates a hash, then created a string for the resume text hash entry, and am trying to use the .find() function to return the entire hash for each instance. What i'd like is if the word "gpa" is used as a search query and it is found in s['resumetext'] for three applicants(rows in .csv file), it prints the id, name, and resume for every row that has it.(All three applicants) As it is right now, my program prints the first row in the .csv file(print resume['id'], resume['name'], resume['resumetext']) no matter what the searchquery is, whether it's in the resumetext or not. lastly, are there better ways to doing this, by searching word documents, pdf's and .txt files in a folder for specific words using python (i've just started reading about the re module and am wondering if this may be the route, rather than putting everything in a .csv file.) def find_details(id2find): resumes_f=open("resume_data.csv") for each_line in resumes_f: s={} (s['id'], s['name'], s['resumetext']) = each_line.split(";") resumetext = str(s['resumetext']) if resumetext.find(id2find): return(s) else: print "No data matches your search query. Please try again" searchquery = raw_input("please enter your search term") resume = find_details(searchquery) if resume: print resume['id'], resume['name'], resume['resumetext']

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  • Django | passing form values

    - by MMRUser
    I want to create a user sign up process that requires two different forms with the same data one (1st form) is for filling out the data and other one (2nd form) is for displaying the filled data as a summery (before actually saving the data) so then user can view what he/she has filled up... my problem is that how do I pass 1st form's data in to the 2nd one .. I have used the basic Django form manipulation mechanism and passed the form field values to the next form using Django template tags.. if request.method == 'POST': form = Users(request.POST) if form.is_valid(): cd = form.cleaned_data try: name = cd['fullName'] email = cd['emailAdd'] password1 = cd['password'] password2 = cd['password2'] phoneNumber = cd['phoneNumber'] return render_to_response('signup2.html', {'name': name, 'email': email, 'password1': password1, 'password2': password2, 'phone': phone, 'pt': phoneType}) except Exception, ex: return HttpResponse("Error %s" % str(ex)) and from the second from I just displayed those field values using tags and also used hidden fields in order to submit the form with values, like this: <label for="">Email:</label> {{ email }} <input type="hidden" id="" name="email" class="width250" value="{{ email }}" readonly /> It works nicely from the out look, but the real problem is that if someone view the source of the html he can simply get the password even hackers can get through this easily. So how do I avoid this issue.. and I don't want to use Django session since this is just a simple sign up process and no other interactions involved. Thanks.

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  • Python re module becomes 20 times slower when called on greater than 101 different regex

    - by Wiil
    My problem is about parsing log files and removing variable parts on each lines to be able to group them. For instance: s = re.sub(r'(?i)User [_0-9A-z]+ is ', r"User .. is ", s) s = re.sub(r'(?i)Message rejected because : (.*?) \(.+\)', r'Message rejected because : \1 (...)', s) I have about 120+ matching rules like those above. I have found no performances issues while searching successively on 100 different regex. But a huge slow down comes when applying 101 regex. Exact same behavior happens when replacing my rules set by for a in range(100): s = re.sub(r'(?i)caught here'+str(a)+':.+', r'( ... )', s) Got 20 times slower when putting range(101) instead. # range(100) % ./dashlog.py file.bz2 == Took 2.1 seconds. == # range(101) % ./dashlog.py file.bz2 == Took 47.6 seconds. == Why such thing is happening ? And is there any known workaround ? (Happens on Python 2.6.6/2.7.2 on Linux/Windows.)

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  • Python for statement giving an Invalid Syntax error with list

    - by Cold Diamondz
    I have some code in which is throwing an error (I'm using repl.it) import random students = ['s1:0','s2:0','s3:0'] while True: print'\n'*50 print'Ticket Machine'.center(80) print'-'*80 print'1. Clear Student Ticket Values'.center(80) print'2. Draw Tickets'.center(80) menu = raw_input('-'*80+'\nChoose an Option: ') if menu == '1': print'\n'*50 print'CLEARED!' students = ['s1:0','s2:0','s3:0'] raw_input('Press enter to return to the main menu!') elif menu == '2': tickets = [] print'\n'*50 times = int(raw_input('How many tickets to draw? ') for a in students: for i in range(a.split(':')[1]): tickets.append(a.split(':')[0]) for b in range(1,times+1): print str(b) + '. ' + random.choice(tickets) else: print'\n'*50 print'That was not an option!' raw_input('Press enter to return to the main menu!') But it is throwing this error: File "<stdin>", line 19 for a in students: ^ SyntaxError: invalid syntax I am planning on using this in a class, but I can't use it until the bug is fixed, also, student names have been removed for privacy reasons.

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  • String comparison in Python: is vs. ==

    - by Coquelicot
    I noticed a Python script I was writing was acting squirrelly, and traced it to an infinite loop, where the loop condition was "while line is not ''". Running through it in the debugger, it turned out that line was in fact ''. When I changed it to != rather than 'is not', it worked fine. I did some searching, and found this question, the top answer to which seemed to be just what I needed. Except the answer it gave was counter to my experience. Specifically, the answerer wrote: For all built-in Python objects (like strings, lists, dicts, functions, etc.), if x is y, then x==y is also True. I double-checked the type of the variable, and it was in fact of type str (not unicode or something). Is his answer just wrong, or is there something else afoot? Also, is it generally considered better to just use '==' by default, even when comparing int or Boolean values? I've always liked to use 'is' because I find it more aesthetically pleasing and pythonic (which is how I fell into this trap...), but I wonder if it's intended to just be reserved for when you care about finding two objects with the same id.

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  • How to insert several thousand columns into sqlite3?

    - by user291071
    Similar to my last question, but I ran into problem lets say I have a simple dictionary like below but its Big, when I try inserting a big dictionary using the methods below I get operational error for the c.execute(schema) for too many columns so what should be my alternate method to populate an sql databases columns? Using the alter table command and add each one individually? import sqlite3 con = sqlite3.connect('simple.db') c = con.cursor() dic = { 'x1':{'y1':1.0,'y2':0.0}, 'x2':{'y1':0.0,'y2':2.0,'joe bla':1.5}, 'x3':{'y2':2.0,'y3 45 etc':1.5} } # 1. Find the unique column names. columns = set() for _, cols in dic.items(): for key, _ in cols.items(): columns.add(key) # 2. Create the schema. col_defs = [ # Start with the column for our key name '"row_name" VARCHAR(2) NOT NULL PRIMARY KEY' ] for column in columns: col_defs.append('"%s" REAL NULL' % column) schema = "CREATE TABLE simple (%s);" % ",".join(col_defs) c.execute(schema) # 3. Loop through each row for row_name, cols in dic.items(): # Compile the data we have for this row. col_names = cols.keys() col_values = [str(val) for val in cols.values()] # Insert it. sql = 'INSERT INTO simple ("row_name", "%s") VALUES ("%s", "%s");' % ( '","'.join(col_names), row_name, '","'.join(col_values) )

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  • Returning C++ objects from Windows DLL

    - by R Samuel Klatchko
    Due to how Microsoft implements the heap in their non-DLL versions of the runtime, returning a C++ object from a DLL can cause problems: // dll.h DLL_EXPORT std::string somefunc(); and: // app.c - not part of DLL but in the main executable void doit() { std::string str(somefunc()); } The above code runs fine provided both the DLL and the EXE are built with the Multi-threaded DLL runtime library. But if the DLL and EXE are built without the DLL runtime library (either the single or multi-threaded versions), the code above fails (with a debug runtime, the code aborts immediately due to the assertion _CrtIsValidHeapPointer(pUserData) failing; with a non-debug runtime the heap gets corrupted and the program eventually fails elsewhere). Two questions: Is there a way to solve this other then requiring that all code use the DLL runtime? For people who distribute their libraries to third parties, how do you handle this? Do you not use C++ objects in your API? Do you require users of your library to use the DLL runtime? Something else?

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  • Javascript memory leak/ performance issue?

    - by Tom
    I just cannot for the life of me figure out this memory leak in Internet Explorer. insertTags simple takes string str and places each word within start and end tags for HTML (usually anchor tags). transliterate is for arabic numbers, and replaces normal numbers 0-9 with a &#..n; XML identity for their arabic counterparts. fragment = document.createDocumentFragment(); for (i = 0, e = response.verses.length; i < e; i++) { fragment.appendChild((function(){ p = document.createElement('p'); p.setAttribute('lang', (response.unicode) ? 'ar' : 'en'); p.innerHTML = ((response.unicode) ? (response.surah + ':' + (i+1)).transliterate() : response.surah + ':' + (i+1)) + ' ' + insertTags(response.verses[i], '<a href="#" onclick="window.popup(this);return false;" class="match">', '</a>'); try { return p } finally { p = null; } })()); } params[0].appendChild( fragment ); fragment = null; I would love some links other than MSDN and about.com, because neither of them have sufficiently explained to me why my script leaks memory. I am sure this is the problem, because without it everything runs fast (but nothing displays). I've read that doing a lot of DOM manipulations can be dangerous, but the for loops a max of 286 times (# of verses in surah 2, the longest surah in the Qur'an).

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  • "Function object is unsubscriptable" in basic integer to string mapping function

    - by IanWhalen
    I'm trying to write a function to return the word string of any number less than 1000. Everytime I run my code at the interactive prompt it appears to work without issue but when I try to import wordify and run it with a test number higher than 20 it fails as "TypeError: 'function' object is unsubscriptable". Based on the error message, it seems the issue is when it tries to index numString (for example trying to extract the number 4 out of the test case of n = 24) and the compiler thinks numString is a function instead of a string. since the first line of the function is me defining numString as a string of the variable n, I'm not really sure why that is. Any help in getting around this error, or even just help in explaining why I'm seeing it, would be awesome. def wordify(n): # Convert n to a string to parse out ones, tens and hundreds later. numString = str(n) # N less than 20 is hard-coded. if n < 21: return numToWordMap(n) # N between 21 and 99 parses ones and tens then concatenates. elif n < 100: onesNum = numString[-1] ones = numToWordMap(int(onesNum)) tensNum = numString[-2] tens = numToWordMap(int(tensNum)*10) return tens+ones else: # TODO pass def numToWordMap(num): mapping = { 0:"", 1:"one", 2:"two", 3:"three", 4:"four", 5:"five", 6:"six", 7:"seven", 8:"eight", 9:"nine", 10:"ten", 11:"eleven", 12:"twelve", 13:"thirteen", 14:"fourteen", 15:"fifteen", 16:"sixteen", 17:"seventeen", 18:"eighteen", 19:"nineteen", 20:"twenty", 30:"thirty", 40:"fourty", 50:"fifty", 60:"sixty", 70:"seventy", 80:"eighty", 90:"ninety", 100:"onehundred", 200:"twohundred", 300:"threehundred", 400:"fourhundred", 500:"fivehundred", 600:"sixhundred", 700:"sevenhundred", 800:"eighthundred", 900:"ninehundred", } return mapping[num] if __name__ == '__main__': pass

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  • Unable to write to a text file

    - by chrissygormley
    Hello, I am running some tests and need to write to a file. When I run the test's the open = (file, 'r+') does not write to the file. The test script is below: class GetDetailsIP(TestGet): def runTest(self): self.category = ['PTZ'] try: # This run's and return's a value result = self.client.service.Get(self.category) mylogfile = open("test.txt", "r+") print >>mylogfile, result result = ("".join(mylogfile.readlines()[2])) result = str(result.split(':')[1].lstrip("//").split("/")[0]) mylogfile.close() except suds.WebFault, e: assert False except Exception, e: pass finally: if 'result' in locals(): self.assertEquals(result, self.camera_ip) else: assert False When this test run's, no value has been entered into the text file and a value is returned in the variable result. I havw also tried mylogfile.write(result). If the file does not exist is claim's the file does not exist and doesn't create one. Could this be a permission problem where python is not allowed to create a file? I have made sure that all other read's to this file are closed so I the file should not be locked. Can anyone offer any suggestion why this is happening? Thanks

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  • Trying to get focus onto JTextPane after doubleclicking on JList element (Java)

    - by Alex Cheng
    Hi all. Problem: I have the following JList which I add to the textPane, and show it upon the caret moving. However, after double clicking on the Jlist element, the text gets inserted, but the caret is not appearing on the JTextPane. This is the following code: listForSuggestion = new JList(str.toArray()); listForSuggestion.setSelectionMode(ListSelectionModel.SINGLE_SELECTION); listForSuggestion.setSelectedIndex(0); listForSuggestion.setVisibleRowCount(visibleRowCount); listScrollPane = new JScrollPane(listForSuggestion); MouseListener mouseListener = new MouseAdapter() { @Override public void mouseClicked(MouseEvent mouseEvent) { JList theList = (JList) mouseEvent.getSource(); if (mouseEvent.getClickCount() == 2) { int index = theList.locationToIndex(mouseEvent.getPoint()); if (index >= 0) { Object o = theList.getModel().getElementAt(index); //System.out.println("Double-clicked on: " + o.toString()); //Set the double clicked text to appear on textPane String completion = o.toString(); int num= textPane.getCaretPosition(); textPane.select(num, num); textPane.replaceSelection(completion); textPane.setCaretPosition(num + completion.length()); int pos = textPane.getSelectionEnd(); textPane.select(pos, pos); textPane.replaceSelection(""); textPane.setCaretPosition(pos); textPane.moveCaretPosition(pos); } } theList.clearSelection(); Any idea on how to "de-focus" the selection on the Jlist, or make the caret appear on the JTextPane after the text insertion? I'll elaborate more if this is not clear enough. Please help, thanks!

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  • Android: Having trouble getting html from webpage

    - by Kyle
    Hi, I'm writing an android application that is supposed to get the html from a php page and use the parsed data from thepage. I've searched for this issue on here, and ended up using some code from an example another poster put up. Here is my code so far: HttpClient client = new DefaultHttpClient(); HttpGet request = new HttpGet(url); try { Log.d("first","first"); HttpResponse response = client.execute(request); String html = ""; Log.d("second","second"); InputStream in = response.getEntity().getContent(); Log.d("third","third"); BufferedReader reader = new BufferedReader(new InputStreamReader(in)); Log.d("fourth","fourth"); StringBuilder str = new StringBuilder(); String line = null; Log.d("fifth","fifth"); while((line = reader.readLine()) != null) { Log.d("request line",line); } in.close(); } catch (ClientProtocolException e) { } catch (IOException e) { // TODO Auto-generated catch block Log.d("error", "error"); } Log.d("end","end"); } Like I said before, the url is a php page. Whenever I run this code, it prints out the first first message, but then prints out the error error message and then finally the end end message. I've tried modifying the headers, but I've had no luck with it. Any help would be greatly appreciated as I don't know what I'm doing wrong. Thanks!

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  • How to make "int" parse blank strings?

    - by Alex B
    I have a parsing system for fixed-length text records based on a layout table: parse_table = [\ ('name', type, length), .... ('numeric_field', int, 10), # int example ('textc_field', str, 100), # string example ... ] The idea is that given a table for a message type, I just go through the string, and reconstruct a dictionary out of it, according to entries in the table. Now, I can handle strings and proper integers, but int() will not parse all-spaces fields (for a good reason, of course). I wanted to handle it by defining a subclass of int that handles blank strings. This way I could go and change the type of appropriate table entries without introducing additional kludges in the parsing code (like filters), and it would "just work". But I can't figure out how to override the constructor of a build-in type in a sub-type, as defining constructor in the subclass does not seem to help. I feel I'm missing something fundamental here about how Python built-in types work. How should I approach this? I'm also open to alternatives that don't add too much complexity.

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  • How do C and C++ interpreters bind identifiers to functions

    - by sub
    I'm talking about C and/or C++ here as this are the only languages I know used for interpreters where the following could be a problem: If we have an interpreted language X how can a library written for it add functions to the language which can then be called from within programs written in the language? PHP example: substr( $str, 5, 10 ); How is the function substr added to the "function pool" of PHP so it can be called from within scripts? It is easy for PHP storing all registered function names in an array and searching through it as a function is called in a script. However, as there obviously is no eval in C(++), how can the function then be called? I assume PHP doesn't have 100MB of code like: if( identifier == "substr" ) { return PHP_SUBSTR(...); } else if( ... ) { ... } Ha ha, that would be pretty funny. I hope you have understood my question so far. How do C/C++ interpreters solve this problem? How can I solve this for my own experimental toy interpreter?

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  • parse a special xml in python

    - by zhaojing
    I have s special xml file like below: <alarm-dictionary source="DDD" type="ProxyComponent"> <alarm code="402" severity="Alarm" name="DDM_Alarm_402"> <message>Database memory usage low threshold crossed</message> <description>dnKinds = database type = quality_of_service perceived_severity = minor probable_cause = thresholdCrossed additional_text = Database memory usage low threshold crossed </description> </alarm> ... </alarm-dictionary> I know in python, I can get the "alarm code", "severity" in tag alarm by: for alarm_tag in dom.getElementsByTagName('alarm'): if alarm_tag.hasAttribute('code'): alarmcode = str(alarm_tag.getAttribute('code')) And I can get the text in tag message like below: for messages_tag in dom.getElementsByTagName('message'): messages = "" for message_tag in messages_tag.childNodes: if message_tag.nodeType in (message_tag.TEXT_NODE, message_tag.CDATA_SECTION_NODE): messages += message_tag.data But I also want to get the value like dnkind(database), type(quality_of_service), perceived_severity(thresholdCrossed) and probable_cause(Database memory usage low threshold crossed ) in tag description. That is, I also want to parse the content in the tag in xml. Could anyone help me with this? Thanks a lot!

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  • C++ compiler error on template specialization

    - by user231536
    I would like to specialize a template method for a class C that is itself templated by an int parameter. How do I do this? template <int D=1> class C { static std::string foo () { stringstream ss; ss << D << endl; return ss.str();} }; template <class X> void test() { cout << "This is a test" << endl;} template <> template <int D> void test<C<D> > () {cout << C<D>::foo() << endl;} The specialization for test() fails with "Too many template parameter lists in declaration of void test()".

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  • Get value of selected field from a dropdown list

    - by 47
    I have this class in my model: class ServiceCharge(models.Model): name = models.CharField(max_length=30) amount = models.PositiveIntegerField() extends_membership = models.BooleanField(default=False) def __unicode__(self): return str(self.name) What I want to have is in the form for charging users a service charge, when a charge is selected from the dropdown menu, the two values for amount and extends_membership are updated on the form depending on the selected charge. My forms.py: class vModelChoiceField(forms.ModelChoiceField): def label_from_instance(self, obj): return "%s" % obj.name class PayServiceChargeForm(PaymentsForm): service_charge = vModelChoiceField(queryset=ServiceCharge.objects.all(), empty_label=" ") class Meta(PaymentsForm.Meta): exclude = ('member', 'payment_type', 'transacted_by', 'description') Then the form template: <table border="0"> <tr> <td><strong>{% trans "Service Charge" %}</strong></td> <td>{{ form.service_charge }}</td> <td><strong>{% trans "Extends Membership" %}</strong></td> <td>{{ form.extends_membership }}</td> </tr> <tr> <td valign="top"><strong>{% trans "Expiry Date" %}</strong></td> <td valign="top">{{ form.expiry_date }}</td> <td valign="top"><strong>{% trans "Amount" %}</strong></td> <td>{{ form.amount }}</td> </tr> </table> I was trying out some jQuery but I got stuck after getting the currently selected charge: <script type="text/javascript"> $(document).ready(function(){ $("#id_service_charge").change(onSelectChange); }); function onSelectChange(){ var selected = $("#id_service_charge option:selected"); var output = ""; if(selected.val() != 0){ charge = selected.val(); .... (update values) .... } } </script>

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  • How to view my Android app created database, via my android app?

    - by suufang
    I'm creating an application that collects users location (Cell broadcast location code) and saves that location with a name of users option, for example say my CB location code is 546034, now my app allows me to store that location code with a name of my choice say 'Home'. So, essentially my app has that following modules, To collect users CB location. To collect a custom name from user of that location. To store these values in a database. I've succeeded in doing all the above modules. I have a sub-module for my third module which has an option for user, of showing and deleting the database values, the screen shot looks as follows, Now, Users should be able to view and delete entries when he chooses the option 'View my database of locations' I've learned how to query my database values and I'm stuck with creating a list view and providing the delete option. My code for getting the database values and querying values goes as follows, submit.setOnClickListener(new View.OnClickListener() { public void onClick(View arg0) { String locname = name.getText().toString(); if(locname.length()==0) { Toast.makeText(getBaseContext(), "Please enter the location name, for example 'Home'.", Toast.LENGTH_LONG).show(); } else { SQLiteDatabase cd = openOrCreateDatabase("mydata", MODE_WORLD_READABLE, null); cd.execSQL("CREATE TABLE IF NOT EXISTS MLITable (CblocationCode INT(10), CblocationName VARCHAR);"); cd.execSQL("INSERT INTO MLITable VALUES ('"+str+ "','"+locname+ "');"); cd.close(); Toast.makeText(getBaseContext(), "value successfully entered.", Toast.LENGTH_LONG).show(); } } }); viewdb.setOnClickListener(new View.OnClickListener() { public void onClick(View arg0) { // here comes the code for viewing the database and deleting SQLiteDatabase db = openOrCreateDatabase("mydata", MODE_WORLD_READABLE, null); Cursor c = db.rawQuery("SELECT * FROM MLITble", null); db.close(); } }); I can see that I've read the table values, but I'm not able to create a display for those values. Help required. Thank you.

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  • Is safe ( documented behaviour? ) to delete the domain of an iterator in execution

    - by PoorLuzer
    I wanted to know if is safe ( documented behaviour? ) to delete the domain space of an iterator in execution in Python. Consider the code: import os import sys sampleSpace = [ x*x for x in range( 7 ) ] print sampleSpace for dx in sampleSpace: print str( dx ) if dx == 1: del sampleSpace[ 1 ] del sampleSpace[ 3 ] elif dx == 25: del sampleSpace[ -1 ] print sampleSpace 'sampleSpace' is what I call 'the domain space of an iterator' ( if there is a more appropriate word/phrase, lemme know ). What I am doing is deleting values from it while the iterator 'dx' is running through it. Here is what I expect from the code : Iteration versus element being pointed to (*): 0: [*0, 1, 4, 9, 16, 25, 36] 1: [0, *1, 4, 9, 16, 25, 36] ( delete 2nd and 5th element after this iteration ) 2: [0, 4, *9, 25, 36] 3: [0, 4, 9, *25, 36] ( delete -1th element after this iteration ) 4: [0, 4, 9, 25*] ( as the iterator points to nothing/end of list, the loop terminates ) .. and here is what I get: [0, 1, 4, 9, 16, 25, 36] 0 1 9 25 [0, 4, 9, 25] As you can see - what I expect is what I get - which is contrary to the behaviour I have had from other languages in such a scenario. Hence - I wanted to ask you if there is some rule like "the iterator becomes invalid if you mutate its space during iteration" in Python? Is it safe ( documented behaviour? ) in Python to do stuff like this?

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  • Adding fields to Django form dynamically (and cleanly)

    - by scott
    Hey guys, I know this question has been brought up numerous times, but I'm not quite getting the full implementation. As you can see below, I've got a form that I can dynamically tell how many rows to create. How can I create an "Add Row" link that tells the view how many rows to create? I would really like to do it without augmenting the url... # views.py def myView(request): if request.method == "POST": form = MyForm(request.POST, num_rows=1) if form.is_valid(): return render_to_response('myform_result.html', context_instance=RequestContext(request)) else: form = MyForm(num_rows=1) return render_to_response('myform.html', {'form':form}, context_instance=RequestContext(request)) # forms.py class MyForm(forms.Form): def __init__(self, *args, **kwargs): num_rows = kwargs.pop('num_rows',1) super(MyForm, self).__init__(*args, **kwargs) for row in range(0, num_rows): field = forms.CharField(label="Row") self.fields[str(row)] = field # myform.html http://example.com/myform <form action="." method="POST" accept-charset="utf-8"> <ul> {% for field in form %} <li style="margin-top:.25em"> <span class="normal">{{ field.label }}</span> {{ field }} <span class="formError">{{ field.errors }}</span> </li> {% endfor %} </ul> <input type="submit" value="Save"> </form> <a href="ADD_ANOTHER_ROW?">+ Add Row</a>

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  • Android: Calculator on showing 0 immediately after the dot

    - by pearmak
    I am now working on a calculator, and everything works fine except for decimal places. The calculator contains 2 displays actually, one is called fakedisplay for actual operations, and one is called Display, for presenting the desired format, ie adding commas. When pressing 12345.678, Display will follow fakedisplay and present as 12,345.678, but if i press 12345.009, the fakedisplay will work normally as 12345.009, but the Display stuck as 12,345 until 9 is pressed, and at that time it will show 12,345.009 normally. However, it is strange that when the user presses 0, there is no response, and until pressing 9, 009 will then immediately append. I know this arise from the parsing code, but based on this, how could I amend the following code? I really cannot think of any solution... Many thanks for all your advice! one.setOnClickListener(new View.OnClickListener() { if (str.length()<15) {Fakedisplay.append("1");} DecimalFormat myFormatter1 = new DecimalFormat("###,###,###,###.#################"); String str1=Fakedisplay.getText().toString(); String stripped1 = Double.valueOf(str1).toString(); stripped1 = myFormatter1.format(Double.valueOf(stripped1)); if (stripped1.endsWith(".0")) stripped1 = stripped1.substring(0, stripped1.length() - 2); Display.setText(stripped1);

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  • Memory allocation patterns in C++

    - by Mahatma
    I am confused about the memory allocation in C++ in terms of the memory areas such as Const data area, Stack, Heap, Freestore, Heap and Global/Static area. I would like to understand the memory allocation pattern in the following snippet. Can anyone help me to understand this. If there any thing more apart from the variable types mentioned in the example to help understand the concept better please alter the example. class FooBar { int n; //Stored in stack? public: int pubVar; //stored in stack? void foo(int param) //param stored in stack { int *pp = new int; //int is allocated on heap. n = param; static int nStat; //Stored in static area of memory int nLoc; //stored in stack? string str = "mystring"; //stored in stack? .. if(CONDITION) { static int nSIf; //stored in static area of memory int loopvar; //stored in stack .. } } } int main(int) { Foobar bar; //bar stored in stack? or a part of it? Foobar *pBar; //pBar is stored in stack pBar = new Foobar(); //the object is created in heap? What part of the object is stored on heap } EDIT: What confuses me is, if pBar = new Foobar(); stores the object on the heap, how come int nLoc; and int pubVar;, that are components of the object stored on stack? Sounds contradictory to me. Shouldn't the lifetime of pubvar and pBar be the same?

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  • What is wrong with this append func in C

    - by LuckySlevin
    My Struct Definitions. typedef struct inner_list {char word[100]; inner_list*next;} inner_list; typedef struct outer_list { char word [100]; inner_list * head; outer_list * next; } outer_list; And The problem part: void append(outer_list **q,char num[100],inner_list *p) { outer_list *temp,*r; temp = *q; char *str; if(*q==NULL) { temp = (outer_list *)malloc(sizeof(outer_list)); strcpy(temp->word,num); temp->head = p; temp->next=NULL; *q=temp; } else { temp = *q; while(temp->next !=NULL) { temp=temp->next; } r = (outer_list *)malloc(sizeof(outer_list)); strcpy(r->word,num); temp->head = p; r->next=NULL; temp->next=r; } } I don't know what is i'm doing wrong in this append function i'm sending a char array and a linked list to be stored another linked list. But i can't store the linked list in another linked list. I couldn't figure out the problem. Any ideas?

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