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In PHP, how do you change the key of an array element?
I have an associative array in the form key => value where key is a numerical value, however it is not a sequential numerical value. The key is actually an ID number and the value is a count. This is fine for most instances, however I want a function that gets the human-readable name of the arr...
Clean ways to write multiple 'for' loops
For an array with multiple dimensions, we usually need to write a for loop for each of its dimensions. For example:
16 An...
Is Fortran easier to optimize than C for heavy calculations?
...ounterpart after optimization. Why so? If you write values into the output array, you may change the values of matrix. After all, the pointers could overlap and point to the same chunk of memory (including the int pointer!). The C compiler is forced to reload the four matrix values from memory for a...
GET URL parameter in PHP
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$_GET is not a function or language construct—it's just a variable (an array). Try:
<?php
echo $_GET['link'];
In particular, it's a superglobal: a built-in variable that's populated by PHP and is available in all scopes (you can use it from inside a function without the global keyword).
S...
Extract first item of each sublist
...my favorite) use numpy:
>>> import numpy as np
>>> a=np.array([[1,2,3],[11,12,13],[21,22,23]])
>>> a
array([[ 1, 2, 3],
[11, 12, 13],
[21, 22, 23]])
>>> a[:,0]
array([ 1, 11, 21])
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Generate unique random numbers between 1 and 100
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For example: To generate 8 unique random numbers and store them to an array, you can simply do this:
var arr = [];
while(arr.length < 8){
var r = Math.floor(Math.random() * 100) + 1;
if(arr.indexOf(r) === -1) arr.push(r);
}
console.log(arr);
...
Why are elementwise additions much faster in separate loops than in a combined loop?
...nk/way conflicts.
If I've guessed correctly on how you are allocating your arrays, they are likely to be aligned to the page line.
This means that all your accesses in each loop will fall on the same cache way. However, Intel processors have had 8-way L1 cache associativity for a while. But in reali...
Multidimensional Array [][] vs [,] [duplicate]
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One is an array of arrays, and one is a 2d array. The former can be jagged, the latter is uniform.
That is, a double[][] can validly be:
double[][] x = new double[5][];
x[0] = new double[10];
x[1] = new double[5];
x[2] = new double...
Append a NumPy array to a NumPy array
I have a numpy_array. Something like [ a b c ] .
9 Answers
9
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Is it better to use std::memcpy() or std::copy() in terms to performance?
...sts that std::copy could not use in my MD5 tests. In the SHA-2 tests, both arrays were created in the same function that called std::copy / memcpy. In my MD5 tests, one of the arrays was passed in to the function as a function parameter.
I did a little bit more testing to see what I could do to mak...