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  • Empty dict-like collection problem in SQLAlchemy

    - by maksymko
    I have a mapping in SQLAlchemy that looks like this: t_property_value = sa.Table('property_value', MetaData, autoload = True, autoload_with = engine) orm.mapper(PropertyValue, t_property_value) t_estate = sa.Table('estate', MetaData, autoload = True, autoload_with = engine) orm.mapper(Estate, t_estate, properties = dict( property_hash = orm.relation(PropertyValue, collection_class = column_mapped_collection(t_property_value.c.property_id)) )) Now, everything seems to be fine, when I load the Estate object and it has some relations to PropertyValue objects. However, when it does not, then property_hash attribute is None, instead of being something dict-like, so I can not add new relations like this: estate.property_hash[prop_id] = PropertyValue(...) because I get the "'NoneType' object does not support item assignment" error. So, is there any way to force SQLAlchemy to create proper empty collection?

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  • Suggestions for a django db structure

    - by rh0dium
    Hi Say I have the unknown number of questions. For example: Is the sky blue [y/n] What date were your born on [date] What is pi [3.14] What is a large integ [100] Now each of these questions poses a different but very type specific answer (boolean, date, float, int). Natively django can happily deal with these in a model. class SkyModel(models.Model): question = models.CharField("Is the sky blue") answer = models.BooleanField(default=False) class BirthModel(models.Model): question = models.CharField("What date were your born on") answer = models.DateTimeField(default=today) class PiModel(models.Model) question = models.CharField("What is pi") answer = models.FloatField() But this has the obvious problem in that each question has a specific model - so if we need to add a question later I have to change the database. Yuck. So now I want to get fancy - How do a set up a model where by the answer type conversion happens automagically? ANSWER_TYPES = ( ('boolean', 'boolean'), ('date', 'date'), ('float', 'float'), ('int', 'int'), ('char', 'char'), ) class Questions(models.model): question = models.CharField(() answer = models.CharField() answer_type = models.CharField(choices = ANSWER_TYPES) default = models.CharField() So in theory this would do the following: When I build up my views I look at the type of answer and ensure that I only put in that value. But when I want to pull that answer back out it will return the data in the format specified by the answer_type. Example 3.14 comes back out as a float not as a str. How can I perform this sort of automagic transformation? Or can someone suggest a better way to do this? Thanks much!!

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  • Diminishing programmer wants to get back to programming

    - by Marcus TV
    I last programmed actively in 2002. It is almost 8 years now. I learned C and then moved to Visual Basic for our thesis project in the university. I would like to ask suggestions on what programming language should I learn and put to profitability use in areas such as desktop applications, web development, and database applications.

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  • Possible to change function name in definition?

    - by Bird Jaguar IV
    I tried several ways to change the function name in the definition, but they failed. >>> def f(): pass >>> f.__name__ 'f' >>> def f(): f.__name__ = 'new name' >>> f.__name__ 'f' >>> def f(): self.__name__ = 'new name' >>> f.__name__ 'f' But I can change the name attribute after defining it. >>> def f(): pass >>> f.__name__ = 'new name' >>> f.__name__ 'new name' Any way to change/set it in the definition (other than using a decorator)?

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  • subplot matplotlib wrong syntax

    - by madptr
    I am using matplotlib to subplot in a loop. For instance, i would like to subplot 49 data sets, and from the doc, i implemented it this way; import numpy as np import matplotlib.pyplot as plt X1=list(range(0,10000,1)) X1 = [ x/float(10) for x in X1 ] nb_mix = 2 parameters = [] for i in range(49): param = [] Y = [0] * len(X1) for j in range(nb_mix): mean = 5* (1 + (np.random.rand() * 2 - 1 ) * 0.5 ) var = 10* (1 + np.random.rand() * 2 - 1 ) scale = 5* ( 1 + (np.random.rand() * 2 - 1) * 0.5 ) Y = [ Y[k] + scale * np.exp(-((X1[k] - mean)/float(var))**2) for k in range(len(X1)) ] param = param + [[mean, var, scale]] ax = plt.subplot(7, 7, i + 1) ax.plot(X1, Y) parameters = parameters + [param] ax.show() However, i have an index out of range error from i=0 onwards. Where can i do better to have it works ? Thanks

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  • Load image from string

    - by zaf
    Given a string containing jpeg image data, is it possible to load this directly in pygame? I've tried using StringIO but failed and I don't completely understand the 'file-like' object concept. Currently, as a workaround, I'm saving to disk and then loading an image the standard way: # imagestring contains a jpeg f=open('test.jpg','wb') f.write(imagestring) f.close() image=pygame.image.load('test.jpg') Any suggestions on improving this so that we avoid creating a temp file?

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  • Selenium selected option in dropdown not displayed correctly

    - by luckyfool
    I have the following issue with Selenium Webdriver. There are two dropdown menus on a page i am testing "brand" and "items". The options of "items" depend on which brand you choose. I am trying to iterate through all possible choices and print brand-item pairs. I use two possible ways to pick an option from each dropdown menu Using Select(): def retryingSelectOption(name,n): result=False attempts=0 while attempts<5: try: element=Select(driver.find_element_by_name(name)) element.select_by_index(n) print element.all_selected_options[0].text result=True break except StaleElementReferenceException: pass attempts+=1 return result And using .click(): def retryingClickOption(name,n): result=False attempts=0 while attempts<5: try: driver.find_element_by_name(name).find_elements_by_tag_name("option")[n].click() result=True break except StaleElementReferenceException: pass attempts+=1 return result My problem is that at ,what seem to me as random moments (sometimes it works sometimes it does not), even though the above functions return True and printing out the selected option shows me the correct answer, the browser still displays the previous option. So basically Selenium tells me i have picked the right option but the browser displays the previous one.No idea what is wrong.

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  • How to achieve interaction between GUI class with logic class

    - by volting
    Im new to GUI programming, and haven't done much OOP. Im working on a basic calculator app to help me learn GUI design and to brush up on OOP. I understand that anything GUI related should be kept seperate from the logic, but Im unsure how to implement interaction between logic an GUI classes when needed i.e. basically passing variables back and forth... Im using TKinter and when I pass a tkinter variable to my logic it only seems to hold the string PY_VAR0. def on_equal_btn_click(self): self.entryVariable.set(self.entryVariable.get() + "=") calculator = Calc(self.entryVariable) self.entryVariable.set(calculator.calculate()) Im sure that im probably doing something fundamentally wrong and probabaly really stupid, I spent a considerable amount of time experimenting (and searching for answers online) but Im getting no where. Any help would be appreciated. Thanks, V The Full Program (well just enough to show the structure..) import Tkinter class Gui(Tkinter.Tk): def __init__(self,parent): Tkinter.Tk.__init__(self,parent) self.parent = parent self.initialize() def initialize(self): self.grid() self.create_widgets() """ grid config """ #self.grid_columnconfigure(0,weight=1,pad=0) self.resizable(False, False) def create_widgets(self): """row 0 of grid""" """Create Text Entry Box""" self.entryVariable = Tkinter.StringVar() self.entry = Tkinter.Entry(self,width=30,textvariable=self.entryVariable) self.entry.grid(column=0,row=0, columnspan = 3 ) self.entry.bind("<Return>", self.on_press_enter) """create equal button""" equal_btn = Tkinter.Button(self,text="=",width=4,command=self.on_equal_btn_click) equal_btn.grid(column=3, row=0) """row 1 of grid""" """create number 1 button""" number1_btn = Tkinter.Button(self,text="1",width=8,command=self.on_number1_btn_click) number1_btn.grid(column=0, row=1) . . . def on_equal_btn_click(self): self.entryVariable.set(self.entryVariable.get() + "=") calculator = Calc(self.entryVariable) self.entryVariable.set(calculator.calculate()) class Calc(): def __init__(self, equation): self.equation = equation def calculate(self): #TODO: parse string and calculate... return self.equation if __name__ == "__main__": app = Gui(None) app.title('Calculator') app.mainloop()

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  • Django: Extending User Model - Inline User fields in UserProfile

    - by Jack Sparrow
    Is there a way to display User fields under a form that adds/edits a UserProfile model? I am extending default Django User model like this: class UserProfile(models.Model): user = models.OneToOneField(User, unique=True) about = models.TextField(blank=True) I know that it is possible to make a: class UserProfileInlineAdmin(admin.TabularInline): and then inline this in User ModelAdmin but I want to achieve the opposite effect, something like inverse inlining, displaying the fields of the model pointed by the OneToOne Relationship (User) in the page of the model defining the relationship (UserProfile). I don't care if it would be in the admin or in a custom view/template. I just need to know how to achieve this. I've been struggling with ModelForms and Formsets, I know the answer is somewhere there, but my little experience in Django doesn't allow me to come up with the solution yet. A little example would be really helpful!

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  • How to create a non-persistent Elixir/SQLAlchemy object?

    - by siebert
    Hi, because of legacy data which is not available in the database but some external files, I want to create a SQLAlchemy object which contains data read from the external files, but isn't written to the database if I execute session.flush() My code looks like this: try: return session.query(Phone).populate_existing().filter(Phone.mac == ident).one() except: return self.createMockPhoneFromLicenseFile(ident) def createMockPhoneFromLicenseFile(self, ident): # Some code to read necessary data from file deleted.... phone = Phone() phone.mac = foo phone.data = bar phone.state = "Read from legacy file" phone.purchaseOrderPosition = self.getLegacyOrder(ident) # SQLAlchemy magic doesn't seem to work here, probably because we don't insert the created # phone object into the database. So we set the id fields manually. phone.order_id = phone.purchaseOrderPosition.order_id phone.order_position_id = phone.purchaseOrderPosition.order_position_id return phone Everything works fine except that on a session.flush() executed later in the application SQLAlchemy tries to write the created Phone object to the database (which fortunatly doesn't succeed, because phone.state is longer than the data type allows), which breaks the function which issues the flush. Is there any way to prevent SQLAlchemy from trying to write such an object? Ciao, Steffen

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  • Django: What's the correct way to get the requesting IP address?

    - by swisstony
    I'm trying to develop an app using Django 1.1 on Webfaction. I'd like to get the IP address of the incoming request, but when I use request.META['REMOTE_ADDR'] it returns 127.0.0.1. There seems to be a number of different ways of getting the address, such as using HTTP_X_FORWARDED_FOR or plugging in some middleware called SetRemoteAddrFromForwardedFor. Just wondering what the best approach was?

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  • gae error:AttributeError: 'NoneType' object has no attribute 'user_is_member'

    - by zjm1126
    class Thread(db.Model): members = db.StringListProperty() def user_is_member(self, user): return str(user) in self.members and thread = Thread.get(db.Key.from_path('Thread', int(id))) is_member = thread.user_is_member(user) but the error is : Traceback (most recent call last): File "D:\Program Files\Google\google_appengine\google\appengine\ext\webapp\__init__.py", line 511, in __call__ handler.get(*groups) File "D:\Program Files\Google\google_appengine\google\appengine\ext\webapp\util.py", line 62, in check_login handler_method(self, *args) File "D:\zjm_code\forum_blog_gae\main.py", line 222, in get is_member = thread.user_is_member(user) AttributeError: 'NoneType' object has no attribute 'user_is_member' why ? thanks

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  • Elegant Disjunctive Normal Form in Django

    - by Mike
    Let's say I've defined this model: class Identifier(models.Model): user = models.ForeignKey(User) key = models.CharField(max_length=64) value = models.CharField(max_length=255) Each user will have multiple identifiers, each with a key and a value. I am 100% sure I want to keep the design like this, there are external reasons why I'm doing it that I won't go through here, so I'm not interested in changing this. I'd like to develop a function of this sort: def get_users_by_identifiers(**kwargs): # something goes here return users The function will return all users that have one of the key=value pairs specified in **kwargs. Here's an example usage: get_users_by_identifiers(a=1, b=2) This should return all users for whom a=1 or b=2. I've noticed that the way I've set this up, this amounts to a disjunctive normal form...the SQL query would be something like: SELECT DISTINCT(user_id) FROM app_identifier WHERE (key = "a" AND value = "1") OR (key = "b" AND value = "2") ... I feel like there's got to be some elegant way to take the **kwargs input and do a Django filter on it, in just 1-2 lines, to produce this result. I'm new to Django though, so I'm just not sure how to do it. Here's my function now, and I'm completely sure it's not the best way to do it :) def get_users_by_identifiers(**identifiers): users = [] for key, value in identifiers.items(): for identifier in Identifier.objects.filter(key=key, value=value): if not identifier.user in users: users.append(identifier.user) return users Any ideas? :) Thanks!

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  • how to create a theme with QT

    - by Moayyad Yaghi
    hello im looking for a way to make my pyqt interface look nicer by adding a theme to it. im new to Qt and i still have no idea how to add a custom theme for widgets.. so how is that possible ? and is it possible through qt designer ? sorry for my bad english , its my third language. i hope the idea is clear enough . please let me know if something was unclear .. thanks in advace

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  • more efficient way to pickle a string

    - by gatoatigrado
    The pickle module seems to use string escape characters when pickling; this becomes inefficient e.g. on numpy arrays. Consider the following z = numpy.zeros(1000, numpy.uint8) len(z.dumps()) len(cPickle.dumps(z.dumps())) The lengths are 1133 characters and 4249 characters respectively. z.dumps() reveals something like "\x00\x00" (actual zeros in string), but pickle seems to be using the string's repr() function, yielding "'\x00\x00'" (zeros being ascii zeros). i.e. ("0" in z.dumps() == False) and ("0" in cPickle.dumps(z.dumps()) == True)

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  • Serving large generated files using Google App Engine?

    - by John Carter
    Hiya, Presently I have a GAE app that does some offline processing (backs up a user's data), and generates a file that's somewhere in the neighbourhood of 10 - 100 MB. I'm not sure of the best way to serve this file to the user. The two options I'm considering are: Adding some code to the offline processing code that 'spoofs' it as a form upload to the blob store, and going thru the normal blobstore process to serve the file. Having the offline processing code store the file somewhere off of GAE, and serving it from there. Is there a much better approach I'm overlooking? I'm guessing this is functionality that isn't well suited to GAE. I had thought of storing in the datastore as db.Text or Dd.Blob but there I encounter the 1 MB limit. Any input would be appreciated,

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  • Django - partially validating form

    - by aeter
    I'm new to Django, trying to process some forms. I have this form for entering information (creating a new ad) in one template: class Ad(models.Model): ... category = models.CharField("Category",max_length=30, choices=CATEGORIES) sub_category = models.CharField("Subcategory",max_length=4, choices=SUBCATEGORIES) location = models.CharField("Location",max_length=30, blank=True) title = models.CharField("Title",max_length=50) ... I validate it with "is_valid()" just fine. Basically for the second validation (another template) I want to validate only against "category" and "sub_category": In another template, I want to use 2 fields from the same form ("category" and "sub_category") for filtering information - and now the "is_valid()" method would not work correctly, cause it validates the entire form, and I need to validate only 2 fields. I have tried with the following: ... if request.method == 'POST': # If a filter for data has been submitted: form = AdForm(request.POST) try: form = form.clean() category = form.category sub_category = form.sub_category latest_ads_list = Ad.objects.filter(category=category) except ValidationError: latest_ads_list = Ad.objects.all().order_by('pub_date') else: latest_ads_list = Ad.objects.all().order_by('pub_date') form = AdForm() ... but it doesn't work. How can I validate only the 2 fields category and sub_category?

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  • standard geographic tilizing/binning method?

    - by monkut
    I'm trying to learn and understand more about mapping and displaying values on a map. (GIS) At the moment I'M looking to take some values and apply those values to a tile or bin on a map. Ideally I'd like the tile sizes to be uniform, like 100 meters, 500 meters, etc. Is there a standard method for creating uniform tile sizes? Or Are what are common accepted method to deal with this kind of data display? (Currently I'm using geodjango and it's related toolset geos, proj4, etc)

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  • How do I specify a null relation in SQLAlchemy?

    - by Jesse
    Not sure what the correct title for this question should be. I have the following schema: Matters have a one-many relationship to WorkItems. WorkItems have a one-one (or one-zero) relationship to LineItems. I am trying to create the following relation between Matters and WorkItems Matter.unbilled_work_items = orm.relation(WorkItem, primaryjoin = (Matter.id == WorkItem.matter_id) and (WorkItem.line_item_id == None), foreign_keys = [WorkItem.matter_id, WorkItem.line_item_id], viewonly=True ) This throws: AttributeError: '_Null' object has no attribute 'table' That seems to be saying that the second clause in the primaryjoin returns an object of type _Null, but it seems to be expecting something with a "table" attribute. This seems like it should be pretty straightforward to me, am I missing something obvious?

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  • problem on strings, tuple strings

    - by suresh
    Write a function, called constrainedMatchPair which takes three arguments: a tuple representing starting points for the first substring, a tuple representing starting points for the second substring, and the length of the first substring. The function should return a tuple of all members (call it n) of the first tuple for which there is an element in the second tuple (call it k) such that n+m+1 = k, where m is the length of the first substring. Complete the definition def constrainedMatchPair(firstMatch,secondMatch,length):

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  • A faster alternative to Pandas `isin` function

    - by user3576212
    I have a very large data frame df that looks like: ID Value1 Value2 1345 3.2 332 1355 2.2 32 2346 1.0 11 3456 8.9 322 And I have a list that contains a subset of IDs ID_list. I need to have a subset of df for the ID contained in ID_list. Currently, I am using df_sub=df[df.ID.isin(ID_list)] to do it. But it takes a lot time. IDs contained in ID_list doesn't have any pattern, so it's not within certain range. (And I need to apply the same operation to many similar dataframes. I was wondering if there is any faster way to do this. Will it help a lot if make ID as the index? Thanks!

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