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Create list of single item repeated N times
... references to the same list, not n independent empty lists.
Performance testing
At first glance it seems that repeat is the fastest way to create a list with n identical elements:
>>> timeit.timeit('itertools.repeat(0, 10)', 'import itertools', number = 1000000)
0.37095273281943264
>...
How do I use a PriorityQueue?
...ounded.
Here's an example of a priority queue sorting by string length:
// Test.java
import java.util.Comparator;
import java.util.PriorityQueue;
public class Test {
public static void main(String[] args) {
Comparator<String> comparator = new StringLengthComparator();
Prio...
How to count TRUE values in a logical vector
...ome context on the "which is faster question", it's always easiest just to test yourself. I made the vector much larger for comparison:
z <- sample(c(TRUE,FALSE),1000000,rep=TRUE)
system.time(sum(z))
user system elapsed
0.03 0.00 0.03
system.time(length(z[z==TRUE]))
user syste...
Difference Between ViewResult() and ActionResult()
...c as you can. This is especially valuable if you're planning to write unit tests. No more testing return types and/or casting the result.
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How to check whether a pandas DataFrame is empty?
...
To see if a dataframe is empty, I argue that one should test for the length of a dataframe's columns index:
if len(df.columns) == 0: 1
Reason:
According to the Pandas Reference API, there is a distinction between:
an empty dataframe with 0 rows and 0 columns
an empty dataframe w...
What's the proper way to install pip, virtualenv, and distribute for Python?
...ackages/source/v/virtualenv/virtualenv-12.0.7.tar.gz
(or whatever is the latest version!)
Unpack the source tarball
Use the unpacked tarball to create a clean virtual environment. This virtual environment will be used to "bootstrap" others. All of your virtual environments will automatically contai...
Must Dependency Injection come at the expense of Encapsulation?
...setter methods. However, this is not necessarily true - I know that the latest versions of the Spring DI framework in Java, for example, let you annotate private fields (e.g. with @Autowired) and the dependency will be set via reflection without you needing to expose the dependency through any of t...
Private properties in JavaScript ES6 classes
...t.
class Something {
#property;
constructor(){
this.#property = "test";
}
#privateMethod() {
return 'hello world';
}
getPrivateMessage() {
return this.#privateMethod();
}
}
const instance = new Something();
console.log(instance.property); //=> undefined
console.lo...
JavaScript loop through json array?
...s. The referenced question has a lengthy discussion about pros and cons.
Test with for(var i ...
But it seems that the follwing is quite save:
for(var i = 0; i < array.length; i += 1)
Although a test in chrome had the following result
var ar = [];
ar[0] = "a";
ar[1] = "b";
ar[4] = "c";
f...
What is the best (idiomatic) way to check the type of a Python variable? [duplicate]
...er heavy with theory and quite a lot to consume when the goal is to simply test if something is a dict or string. Is there additional effort to implement ABCs, and (especially for a simple use case) is the added effort worth it?
– Mike S
Jun 12 '15 at 14:52
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