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How do I find the location of my Python site-packages directory?
How do I find the location of my site-packages directory?
21 Answers
21
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Principal component analysis in Python
I'd like to use principal component analysis (PCA) for dimensionality reduction. Does numpy or scipy already have it, or do I have to roll my own using numpy.linalg.eigh ?
...
Forward an invocation of a variadic function in C
In C, is it possible to forward the invocation of a variadic function? As in,
12 Answers
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Threading pool similar to the multiprocessing Pool?
...y is a thread-based Pool interface in the multiprocessing module, however it is hidden somewhat and not properly documented.
It can be imported via
from multiprocessing.pool import ThreadPool
It is implemented using a dummy Process class wrapping a python thread. This thread-based Process clas...
List changes unexpectedly after assignment. How do I clone or copy it to prevent this?
...t everytime. Why is this, and how can I clone or copy the list to prevent it?
22 Answers
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Class method decorator with self arguments?
...
Yes. Instead of passing in the instance attribute at class definition time, check it at runtime:
def check_authorization(f):
def wrapper(*args):
print args[0].url
return f(*args)
return wrapper
class Client(object):
def __init__(self, url):
self.url =...
How do I change the working directory in Python?
...
You can change the working directory with:
import os
os.chdir(path)
There are two best practices to follow when using this method:
Catch the exception (WindowsError, OSError) on invalid path. If the exception is thrown, do not perform any recursive operati...
What's the difference between a file descriptor and file pointer?
...
You pass "naked" file descriptors to actual Unix calls, such as read(), write() and so on.
A FILE pointer is a C standard library-level construct, used to represent a file. The FILE wraps the file descriptor, and adds buffering and other features to make I/O easier.
You pass FILE pointers to stan...
How to extract the decision rules from scikit-learn decision-tree?
...hon function. Here's an example output for a tree that is trying to return its input, a number between 0 and 10.
def tree(f0):
if f0 <= 6.0:
if f0 <= 1.5:
return [[ 0.]]
else: # if f0 > 1.5
if f0 <= 4.5:
if f0 <= 3.5:
return [[ 3.]]
el...
What is the most accurate way to retrieve a user's correct IP address in PHP?
...ode seems to be pretty complete already, I cannot see any possible bugs in it (aside from the usual IP caveats), I would change the validate_ip() function to rely on the filter extension though:
public function validate_ip($ip)
{
if (filter_var($ip, FILTER_VALIDATE_IP, FILTER_FLAG_NO_PRIV_RANGE ...