Hi,
Fastest way to uniqify a list in Python without preserving order? I saw many complicated solutions on Internet - could they be faster then simply:
list(set([a,b,c,a]))
?
I wrote PyQt application. After it's start I close it (GUI), but timer don't stops and Python sometimes freezes. Only thing to unfreeze it - Ctrl-C, after which following message appears:
Traceback (most recent call last):
File "", line 262, in timerEvent
KeyboardInterrupt
timer don't stops again, and CPython works very slowly. How to avoid this problem?
how can I use wild cars like '*' when getting a list of files inside a directory in Python? for example, I want something like:
os.listdir('foo/*bar*/*.txt')
which would return a list of all the files ending in .txt in directories that have bar in their name inside of the foo parent directory.
how can I do this?
thanks.
I am creating a sort of "Command line" in Python. I already added a few functions, such as changing login/password, executing, etc., But is it possible to browse files in the directory that the main file is in with a command/module, or will I have to make the module myself and use the import command? Same thing with changing directories to view, too.
In Javascript I can do this:
function A(x) { return x || 3; }
This returns 3 if x is a "non-truthful" value like 0, null, false, and it returns x otherwise. This is useful for empty arguments, e.g. I can do A() and it will evaluate as 3.
Does Python have an equivalent? I guess I could make one out of the ternary operator a if b else c but was wondering what people use for this.
I'm looking for a way in python to find out which type of file system is being used for a given path. I'm wanting to do this in a cross platform way. On linux I could just grab the output of df -T but that won't work on OSX or windows.
I have a question about idioms and readability, and there seems to be a clash of Python philosophies for this particular case:
I want to build dictionary A from dictionary B. If a specific key does not exist in B, then do nothing and continue on.
Which way is better?
try:
A["blah"] = B["blah"]
except KeyError:
pass
or
if "blah" in B:
A["blah"] = B["blah"]
"Do and ask for forgiveness" vs. "simplicity and explicitness".
Which is better and why?
how to traverse a binary decision tree using python language.
given a tree,i want know how can we travesre from root to required leaf
the feature of the required leaf are given in an dictionary form assume and have to traverse from root to leaf answering the questions at each node with the details given in feature list..
the decision tree node has format ((question)(left tree)(right tree))
while traversing it should answer question at each node and an choose left or right and traverse till leaf?
Since input and raw_input() stop the program from running anymore, I want to use a subprocess to run this program...
while True: print raw_input()
and get its output.
This is what I have as my reading program:
import subprocess
process = subprocess.Popen('python subinput.py', stdout=subprocess.PIPE, stderr=subprocess.PIPE)
while True:
output=process.stdout.read(12)
if output=='' and process.poll()!=None:
break
if output!='':
sys.stdout.write(output)
sys.stdout.flush()
When I run this, the subprocess exits almost as fast as it started. How can I fix this?
Hi,
I need to compare two files and redirect the different lines to third file. I know using diff command i can get the difference . But, is there any way of doing it in python ? Any sample code will be helpful
Can we initialize python objects with statement like this:
a = b = c = None
it seems to me when I did a = b = c = list() will cause circular reference count issue.
Please give your expert advice.
wow i thought i knew python untill tonight.. what is the correct way to do something like this.. heres my code
a = ["one", "two", "three"]
b = a #here i want a complete copy that when b is changed, has absolutely no effect on a
b.append["four"]
print a #a now has "four" in it..
so basically i want to know, instead of the b = a step, how would i correctly make a copy of a list or dictionary so that when b is changed a does not change along with it.. thanks guys
Is there a general convention about exposing members in Python classes? I know that this is a case of "it depends", but maybe there is a rule of thumb.
Private member:
class Node:
def __init__(self):
self.__childs = []
def add_childs(self, *args):
self.__childs += args
node = Node()
node.add_childs("one", "two")
Public member:
class Node2:
def __init__(self):
self.childs = []
node2 = Node2()
node2.childs += "one", "two"
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.
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?
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?
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?
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.
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