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Is there a math nCr function in python? [duplicate]
..., ('a', 'd'), ('b', 'c'), ('b', 'd'), ('c', 'd')]
>>> [''.join(x) for x in itertools.combinations('abcd',2)]
['ab', 'ac', 'ad', 'bc', 'bd', 'cd']
If you just need to compute the formula, use math.factorial:
import math
def nCr(n,r):
f = math.factorial
return f(n) / f(r) / f(n-r)
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Python: most idiomatic way to convert None to empty string?
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I'm keeping the else, but thanks for the str(s) tip so multiple types can be handled. nice!
– Mark Harrison
Jul 1 '09 at 9:39
13
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How to put multiple statements in one line?
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Unfortunately, what you want is not possible with Python (which makes Python close to useless for command-line one-liner programs). Even explicit use of parentheses does not avoid the syntax exception. You can get away with a s...
What's the _ underscore representative of in Swift References?
...y a little bit more.
_ is used to modify external parameter name behavior for methods.
In Local and External Parameter Names for Methods section of the documentation, it says:
Swift gives the first parameter name in a method a local parameter name by default, and gives the second and subsequen...
How to implement the --verbose or -v option into a script?
...d to
# stuff everything to be printed into a single string
for arg in args:
print arg,
print
else:
verboseprint = lambda *a: None # do-nothing function
(Yes, you can define a function in an if statement, and it'll only get defined if the condition is ...
Can you give a Django app a verbose name for use throughout the admin?
... This popular answer recommends using a hack/workaround that was needed before Django 1.7. If you're using 1.7 or above, use an apps.py file as recommended below by iMaGiNiX.
– shacker
Feb 2 '15 at 22:40
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How to get current route in Symfony 2?
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@got a switchwation for you check meta.stackexchange.com/questions/155258/…
– NullPoiиteя
Nov 10 '12 at 6:35
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Coding Practices which enable the compiler/optimizer to make a faster program
...Write to local variables and not output arguments! This can be a huge help for getting around aliasing slowdowns. For example, if your code looks like
void DoSomething(const Foo& foo1, const Foo* foo2, int numFoo, Foo& barOut)
{
for (int i=0; i<numFoo, i++)
{
barOut.mung...
SASS - use variables across multiple files
...e to keep one central .scss file that stores all SASS variable definitions for a project.
6 Answers
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What is the best way to ensure only one instance of a Bash script is running? [duplicate]
...th access to execution. When you are done, just remove the lock. In script form this might look like:
#!/bin/bash
lockfile -r 0 /tmp/the.lock || exit 1
# Do stuff here
rm -f /tmp/the.lock
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