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Creating functions in a loop
...rguments are evaluated immediately when the function is defined:
for i in range(3):
def f(i=i): # <- right here is the important bit
return i
functions.append(f)
To give a little bit of insight into how/why this works: A function's default arguments are stored as an attribute...
Math.random() versus Random.nextInt(int)
...ly distributed bits in its mantissa, so it is uniformly distributed in the range 0 to 1-(2^-53).
Random.nextInt(n) uses Random.next() less than twice on average- it uses it once, and if the value obtained is above the highest multiple of n below MAX_INT it tries again, otherwise is returns the ...
Plotting time in Python with Matplotlib
...e data
x = [datetime.datetime.now() + datetime.timedelta(hours=i) for i in range(12)]
y = [i+random.gauss(0,1) for i,_ in enumerate(x)]
# plot
plt.plot(x,y)
# beautify the x-labels
plt.gcf().autofmt_xdate()
plt.show()
Resulting image:
Here's the same as a scatter plot:
import datetime
impo...
When to use pip requirements file versus install_requires in setup.py?
...tool has a requirements.txt file that pins a particular version or version range of requests, that would seem to create a potential problem for my-web-app, which might have specified a conflicting version/version range.
– Reece
Mar 5 '14 at 21:53
...
When to use AtomicReference in Java?
...a use case for AtomicReference:
Consider this class that acts as a number range, and uses individual AtmomicInteger variables to maintain lower and upper number bounds.
public class NumberRange {
// INVARIANT: lower <= upper
private final AtomicInteger lower = new AtomicInteger(0);
...
How do I revert a Git repository to a previous commit?
...ate revert commits:
git revert a867b4af 25eee4ca 0766c053
# It also takes ranges. This will revert the last two commits:
git revert HEAD~2..HEAD
#Similarly, you can revert a range of commits using commit hashes (non inclusive of first hash):
git revert 0d1d7fc..a867b4a
# Reverting a merge commit
...
How to convert a number to string and vice versa in C++
...cted, for example because there is no numeric data or the number is out-of-range for the type, an exception is thrown (std::invalid_argument or std::out_of_range).
If conversion succeeded and idx is not 0, idx will contain the index of the first character that was not used for decoding. This could ...
Multiprocessing vs Threading Python [duplicate]
...t, niters):
'''
A useless CPU bound function.
'''
for i in range(niters):
result = (result * result * i + 2 * result * i * i + 3) % 10000000
return result
class CpuThread(threading.Thread):
def __init__(self, niters):
super().__init__()
self.niters = ...
Getting the last element of a list
... when you want an element only postpones the inevitable "list index out of range" - and that's what should happen when attempting to get an element from an empty list. For Strings astr[-1:] could be a valid approach since it returns the same type as astr[-1], but I don't think the ':' helps to deal ...
What does the slash mean in help() output?
What does the / mean in Python 3.4's help output for range before the closing parenthesis?
3 Answers
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