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What does $$ mean in the shell?
... locations other folks can write to it's not too difficult on many OSes to predict what PID you're going to have and screw around -- imagine you're running as root and I create /tmp/yourprogname13395 as a symlink pointing to /etc/passwd -- and you write into it.
This is a bad thing to be doing in a...
Why switch is faster than if
... try to place the hottest branch first in the code. This is called "Branch Prediction". For more information on this, see here: https://dzone.com/articles/branch-prediction-in-java
Your experiences may vary. I don't know that the JVM doesn't run a similar optimization on LookupSwitch, but I've lear...
Which UUID version to use?
... ID based on a network card MAC address and a timer. These IDs are easy to predict (given one, I might be able to guess another one) and can be traced back to your network card. It's not recommended to create these.
Version 4: These are generated from random (or pseudo-random) numbers. If you just n...
What is Type-safe?
...ined fashion, and if you're clever enough (I'm not), you should be able to predict what will happen when reading Javascript code.
An example of a type-unsafe programming language is C: reading / writing an array value outside of the array's bounds has an undefined behaviour by specification. It's i...
Position of least significant bit that is set
...itecture dependent. Today's processors are too complex (in terms of branch prediction, cache misses, pipelining) that it's so hard to predict which code is executed faster on which architecture. Decreasing operations from 32 to 9 or things like that might even decrease the performance on some archit...
list.clear() vs list = new ArrayList(); [duplicate]
...epends on a whole range of factors such as:
whether the list size can be predicted beforehand (i.e. can you set the capacity accurately),
whether the list size is variable (i.e. each time it is filled),
how long the lifetime of the list will be in both versions, and
your heap / GC parameters and C...
Is it possible to create a “weak reference” in javascript?
...ou drive your objects through. When an object is stored, the cache keeps a prediction of how much memory the object will take up. For some items, like storing images, this is straight forward to work out. For others this would be more difficult.
When you need an object, you then ask the cache for i...
Is it necessary to write HEAD, BODY and HTML tags?
...actical standpoint you often want browsers to run in "standards mode," for predictability in rendering HTML and CSS. Providing a DOCTYPE and a more structured HTML tree will guarantee more predictable cross-browser results.
...
Avoiding if statement inside a for loop?
..."worrying about the performance".
If this is indeed the case, the branch predictor will have no problem in predicting the (constant) result. As such, this will only cause a mild overhead for mispredictions in the first few iterations. It's nothing to worry about in terms of performance
In this ca...
How do I create test and train samples from one dataframe with pandas?
...r all your lines with this cross-validation. At the end, you will have one prediction for each line of your available training set.
from sklearn.model_selection import KFold
kf = KFold(n_splits=10, random_state=0)
y_hat_all = []
for train_index, test_index in kf.split(X, y):
reg = RandomForestR...