python

Python: For loop problem

I have a simple for loop problem, when i run the code below it prints out series of 'blue green' sequences then a series of 'green' sequences. I want the output to be; if row[4] is equal to 1 to print blue else print green. for row in rows: for i in `row[4]`: if i ==`1`: print 'blue ' el...

How to join list of strings?

Hi all, This is probably seriously easy to solve for most of you but I cannot solve this simply putting str() around it can I? I would like to convert this list: ['A','B','C'] into 'A B C'. Thanks in advance!! ...

How to do Python's zip in C#?

Python's zip function does the following: a = [1, 2, 3] b = [6, 7, 8] zipped = zip(a, b) result [[1, 6], [2, 7], [3, 8]] ...

easy hex/float conversion

I am doing some input/output between a c++ and a python program (only floating point values) python has a nice feature of converting floating point values to hex-numbers and back as you can see in this link: http://docs.python.org/library/stdtypes.html#additional-methods-on-float Is there an easy way in C++ to to something similar? and...

How do I delete a foreign key in SQLAlchemy?

I'm using SQLAlchemy Migrate to keep track of database changes and I'm running into an issue with removing a foreign key. I have two tables, t_new is a new table, and t_exists is an existing table. I need to add t_new, then add a foreign key to t_exists. Then I need to be able to reverse the operation (which is where I'm having troubl...

Thread-safe equivalent to python's time.strptime() ?

Something I wrote throws a lot of AttributeError exceptions when using time.strptime() inside a thread. This only seems to happen on Windows (not on Linux) but whatever- upon a'Googling, it seems that time.strptime() isn't considered thread-safe. Is there a better way to create a datetime object from a string? Current code looks like: ...

Python Question: Year and Day of Year to date?

I have a year value and a day of year and would like to convert to a date (day/month/year). Thanks in advance. :) ...

pyOpenSSL and the WantReadError

I have a socket server that I am trying to move over to SSL on python 2.5, but I've run into a snag with pyOpenSSL. I can't find any good tutorials on using it, so I'm operating largely on guesses. Here is how my server sets up the socket: ctx = SSL.Context(SSL.SSLv23_METHOD) ctx.use_privatekey_file ("mykey.pem") ctx.use_certificate_fi...

Python appengine Query does not work when using a variable.

Hi, I am trying to use a fetcher method to retrieve items from my datastore. If I use the following def getItem(item_id): q = Item.all() q.filter("itemid = ", item_id) It fails because nothing is returned. If I hard code in an item like def getItem(item_id): q = Item.all() q.filter("itemid = ", 9000) it fetches j...

Old desktop programmer wants to create S+S project

I have an idea for a product that I want to be web-based. But because I live in a part of the world where the internet is not always available, there needs to be a client desktop component that is available for when the internet is down. Also, I have been a SQL programmer, a desktop application programmer using dBase, VB and Pascal, and ...

Django | Python creating a JSON response

Hi, I'm trying to convert a server side AJAX response script in to an Django HttpResponse, but apparently it's not working. This is the server-side script /* RECEIVE VALUE */ $validateValue=$_POST['validateValue']; $validateId=$_POST['validateId']; $validateError=$_POST['validateError']; /* RETURN VALUE */ $arrayToJs = arra...

casting raw strings python

in python, given a variable which holds a string is there a quick way to cast that into another raw string variable? the following code should illustrate what im after... def checkEqual(x, y): print True if x==y else False line1 = "hurr..\n..durr" line2 = r"hurr..\n..durr" line3 = "%r"%line1 print "%s \n\n%s \n\n%s \n" % (line1, ...

Is it possible to make a persistent connection between a Python web service and a .Net WCF Client?

I have a .Net 3.5 SOAP client written in C# using the WCF. It's expecting basicHTTPBinding and a persistent connection with HTTP/1.1. I'm trying to create a Python 2.6 application that will act as a web-service for the client. My problem is that the client keeps closing the connection and opening a new one for every command to the web...

Should I worry about circular references in Python?

Suppose I have code that maintains parent/children structure. In such a structure I get circular references, where child points to parent and parent points to child. Should I worry about them? I'm using Python 2.5. I am concerned that they will not be garbage collected and the application will eventually consume all memory. Thanks, Bod...

When to use Python special methods?

I know that classes can implement various special methods, such as __iter__, __setitem__, __len__, __setattr__, and many others. But when should I use them? Can anyone describe typical scenarios when I would want to implement them and they would simplify programming in Python? Thanks, Boda Cydo. ...

os.path.getmtime() doesn't return fraction of a second

I compiled python 2.6.4 for centos 5.3 and find this issue that os.path.getmtime() or os.stat().m_time doesn't have the fraction part. As per docs, if os.stat_float_times() returns True, then it should return float value. In my case, I do see it as float, but no fraction part (it is 0). In [3]: os.path.getmtime('/tmp') Out[3]: 12683391...

Concise way to getattr() and use it if not None in Python

I am finding myself doing the following a bit too often: attr = getattr(obj, 'attr', None) if attr is not None: attr() # Do something, either attr(), or func(attr), or whatever else: # Do something else Is there a more pythonic way of writing that? Is this better? (At least not in performance, IMO.) try: obj.attr() # ...

How to test floats resoults with doctest?

Hi I'm developing a program that makes some floating points calculus. is there any way to test the my functions (which deliver floats) with doctest? ...

datetime command line argument in python 2.4

I want to pass a datetime value into my python script on the command line. My first idea was to use optparse and pass the value in as a string, then use datetime.strptime to convert it to a datetime. This works fine on my machine (python 2.6), but I also need to run this script on machines that are running python 2.4, which doesn't have ...

How to detect an 'image area' percentage inside an image?

Mhh, kinda hard to explain with my poor english ;) So, lets say I have an image, doesnt matter what kind of (gif, jpg, png) with 200x200 pixel size (total area 40000 pixels) This image have a background, that can be trasparent, or every color (but i know the background-color in advance). Lets say that in the middle of this image, ther...