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How to create the most compact mapping n → isprime(n) up to a limit N?
...orithm I usually implement (easy to understand and code) is as follows (in Python):
def isprime(n):
"""Returns True if n is prime."""
if n == 2:
return True
if n == 3:
return True
if n % 2 == 0:
return False
if n % 3 == 0:
return False
i = 5
...
Is it possible to specify your own distance function using scikit-learn K-Means Clustering?
... enough);
in particular, what are your N, dim, k, metric ?
#!/usr/bin/env python
# kmeans.py using any of the 20-odd metrics in scipy.spatial.distance
# kmeanssample 2 pass, first sample sqrt(N)
from __future__ import division
import random
import numpy as np
from scipy.spatial.distance import cdi...
Can I mask an input text in a bat file?
... the command line. For example, you can replace the cscript section with: 'python -c "from getpass import getpass; pwd = getpass(); print pwd;"'
– Cerin
Jul 30 '10 at 17:15
1
...
Shortest distance between a point and a line segment
...to be (that's why I made this).
Implementation of theory by Paul Bourke.
Python:
def dist(x1, y1, x2, y2, x3, y3): # x3,y3 is the point
px = x2-x1
py = y2-y1
norm = px*px + py*py
u = ((x3 - x1) * px + (y3 - y1) * py) / float(norm)
if u > 1:
u = 1
elif u <...
How to check whether a pandas DataFrame is empty?
...
In Python, try/except is cheap and if is expensive. Python is neither Java nor C; here it's Easier to Ask Forgiveness than Permission
– Nick Marinakis
Apr 14 at 1:26
...
What does this square bracket and parenthesis bracket notation mean [first1,last1)?
... programming languages tends to be zero-based, such as C, C++, Javascript, Python, while other languages such as Mathematica, Fortran, Pascal are one-based.
These differences can lead to subtle fence post errors, aka, off-by-one bugs when implementing Mathematical algorithms such as for-loops.
...
Please explain some of Paul Graham's points on Lisp
...about language fundamentals. You wouldn't hear a similar claim of Java, C, Python, Perl, Haskell, etc. as a good beginner's project!
– Matt Curtis
Apr 26 '10 at 0:57
9
...
MongoDB/NoSQL: Keeping Document Change History
...
For users of Python (python 3+, and up of course) , there's HistoricalCollection that's an extension of pymongo's Collection object.
Example from the docs:
from historical_collection.historical import HistoricalCollection
from pymongo i...
Can I have an IF block in DOS batch file?
... msg * with any othe operation...
goto Continue1
)
:Continue1
If exist "C:\Python31" (
msg * 2nd line WORKS FINE rem You can relpace msg * with any othe operation...
goto Continue2
)
:Continue2
If exist "C:\Python31\Lib\site-packages\PyQt4" (
msg * 3th line WORKS FINE rem You can relpace msg *...
Why is exception handling bad?
...either culture-specific (maybe more of a problem in Java or C++ than, say, Python) or domain-specific.
– ddaa
Nov 16 '09 at 10:24
39
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