How are lists in python stored internally? Is it an array? A linked list? Something else?
Or does the interpreter guess at the right structure for each instance based on length, etc.
If the question is implementation dependent, what about the classic CPython?
im trying to build android from source on ubuntu 10.04. when i enter the repo command:
repo init -u git://android.git.kernel.org/platform/manifest.git -b eclair
it get this error back
exec: 23: python: not found
any ideas.
Does anyone know of a memory efficient way to generate very large xml files (e.g. 100-500 MiB) in Python?
I've been utilizing lxml, but memory usage is through the roof.
One of the ideas of Python's design philosophy is "There should be one ... obvious way to do it." (PEP 20), but that can't always be true. I'm specifically referring to (simple) if statements versus boolean evaluation. Consider the following:
if words:
self.words = words
else:
self.words = {}
versus
self.words = words or {}
With such a simple situation, which is preferable, stylistically speaking? With more complicated situations one would choose the if statement for readability, right?
I have a string of HTML stored in a database. Unfortunately it contains characters such as ®
I want to replace these characters by their HTML equivalent, either in the DB itself or using a Find Replace in my Python / Django code.
Any suggestions on how I can do this?
Contents of check.py:
from multiprocessing import Process
import time
import sys
def slp():
time.sleep(30)
f=open("yeah.txt","w")
f.close()
if __name__=="__main__" :
x=Process(target=slp)
x.start()
sys.exit()
In windows 7, from cmd, if I call python check.py, it doesn't immediately exit, but instead waits for 30 seconds. And if I kill cmd, the child dies too- no "yeah.txt" is created.
How do I make ensure the child continues to run even if parent is killed and also that the parent doesn't wait for child process to end?
I am running a multithreaded application(Python2.7.3) in a Intel(R) Core(TM)2 Duo CPU E7500 @ 2.93GHz. I thought it would be using only one core but using the "top" command I see that the python processes are constantly changing the core no. Enabling "SHOW THREADS" in the top command shows diffrent thread processes working on different cores.
Can anyone please explain this? It is bothering me as I know from theory that multithreading is executed on a single core.
Python has string.find() and string.rfind() to get the index of a substring in string.
I wonder, maybe there is something like string.find_all() which can return all founded indexes (not only first from beginning or first from end)?
For example:
string = "test test test test"
print string.find('test') # 0
print string.rfind('test') # 15
#that's the goal
print string.find_all('test') # [0,5,10,15]
So the setup is a slew of proprietary server/client Python applications running on one Linux box (the server) and a set of Windows 7 workstations (the clients). Everything is running smoothly until any of the proprietary Python packages needs updating.
For now I am using distutils eggs which are very easily updated with easy_install, but it is still a manual process which quickly becomes tedious as the number of applications and client workstations grow.
The ideal setup IMHO is to have the Python packages on the server so when a client application is launched on a workstation the client application can check to see whether its current Python packages are up-to-date. If not, the client application should download the newer Python package from the server, install it, and then launch as per normal.
Does this sounds familiar to anyone? I have tried to find alternatives myself, but as far as I can see there is no Python module offering this functionality. Does anyone have any home made solutions for this?
I'm using the following code to hide stderr on Linux/OSX for a Python library I do not control that writes to stderr by default:
f = open("/dev/null","w")
zookeeper.set_log_stream(f)
Is there an easy cross platform alternative to /dev/null? Ideally it would not consume memory since this is a long running process.
I have two floats in Python that I'd like to subtract, i.e.
v1 = float(value1)
v2 = float(value2)
diff = v1 - v2
I want "diff" to be computed upto two significant figures, that is compute it using %.2f of v1 and %.2f of v2. How can I do this? I know how to print v1 and v2 up to two decimals, but not how to do arithmetic like that.
thanks.
Hi,
I am looking for a python SOAP 1.2 client but it seems that it does not exist . All of the existing clients are either not maintainted or only compatible with SOAP 1.1:
suds
SOAPpy
ZSI
Hi
I wrote a matlab code (that easily could be implimented as a function) that convert a series of BMPs to avi. I want a python program to call to this program/function. how do I do it?
thanks
Hi,
I was going over some pages from WikiVS, that I quote from:
because lambdas in Python are restricted to expressions and cannot contain statements
I would like to know what would be a good example (or more) where this restriction would be, preferably compared to the Ruby language.
Thank you for your answers, comments and feedback!
Windows XP, Python 2.5:
hash('http://stackoverflow.com') Result: 1934711907
Google App Engine (http://shell.appspot.com/):
hash('http://stackoverflow.com') Result: -5768830964305142685
Why is that? How can I have a hash function which will give me same results across different platforms (Windows, Linux, Mac)?
Cant download any pyhton windows modules and install. I wanted to experiment with scrapy framework and stackless but unable to install due to error "Python veIrsion 2.6 required, which was not found in the registry".
Trying to install it to
Windows 7, 64 bit machine
For some reason this function confused me:
def protocol(port):
return port == "443" and "https://" or "http://"
Can somebody explain the order of what's happening behind the scenes to make this work the way it does.
I understood it as this until I tried it:
Either A)
def protocol(port):
if port == "443":
if bool("https://"):
return True
elif bool("http://"):
return True
return False
Or B)
def protocol(port):
if port == "443":
return True + "https://"
else:
return True + "http://"
Is this some sort of special case in Python, or am I completely misunderstanding how statements work?
I want to run:
python somescript.py somecommand
But, when I run this I need PYTHONPATH to include a certain directory. I can't just add it to my environment variables because the directory I want to add changes based on what project I'm running. Is there a way to alter PYTHONPATH while running a script? Note: I don't even have a PYTHONPATH variable, so I don't need to worry about appending to it vs overriding it during running of this script.
Hi folks,
I'm having quite a problem deciding how to serve a few Python scripts.
The problem is that the basic functionality could be generalized by this:
do_something()
time.sleep(3)
do_something()
I tried various WSGI servers, but they have all been giving me concurrency limitations, as in I have to specify how many threads to use and so on.
I only wish that the resources on the server be used efficiently and liberally.
Any ideas?
Hi
I have a list of points as shown below
points=[ [x0,y0,v0], [x1,y1,v1], [x2,y2,v2].......... [xn,yn,vn]]
Some of the points have duplicate x,y values. What I want to do is to extract the unique maximum value x,y points
For example, if I have points [1,2,5] [1,1,3] [1,2,7] [1,7,3]
I would like to obtain the list [1,1,3] [1,2,7] [1,7,3]
How can I do this in python
Thanks
I have a system where a central Java controller launches analysis processes, which may be written in C++, Java, or Python (mostly they are C++). All these processes currently run on the same server. What are you suggestions to
Create a central log to which all processes can write to
What if in the future I push some processes to another server. How can I support distributed logging?
Thanks!
Can you please give me a simple, and straightforward python example of sending an HTML e-mail using App Engine? Plaintext is straightforward, but I'm having difficulties with HTML tags.