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Algorithm to return all combinations of k elements from n
...ickly, you'll have problems by 20 elements in your set -- 20C3 = 1140. And if you want to iterate over the set it's best to use a modified gray code algorithm so you aren't holding all of them in memory. These generate the next combination from the previous and avoid repetitions. There are many of t...
How can I convert a zero-terminated byte array to string?
... read. You should save that number and then use it to create your string. If n is the number of bytes read, your code would look like this:
s := string(byteArray[:n])
To convert the full string, this can be used:
s := string(byteArray[:len(byteArray)])
This is equivalent to:
s := string(byteArray...
How to check whether a string contains a substring in JavaScript?
...iler like Babel, a shim library like es6-shim, or this polyfill from MDN:
if (!String.prototype.includes) {
String.prototype.includes = function(search, start) {
'use strict';
if (typeof start !== 'number') {
start = 0;
}
if (start + search.length > this.length) {
...
Get Image size WITHOUT loading image into memory
...In addition the docs say:
open(file, mode=”r”)
Opens and identifies the given image file.
This is a lazy operation; this function identifies the file, but the actual image data is not read from the file until you try to process the data (or call the load method).
Digging deeper...
'sudo gem install' or 'gem install' and gem locations
Running ' sudo gem list --local ' and ' gem list --local ' give me differing results. My gem path is set to my home folder and only contains the gems from ' gem list --local '.
...
Grouping functions (tapply, by, aggregate) and the *apply family
... ?apply). There are enough of them, though, that beginning useRs may have difficulty deciding which one is appropriate for their situation or even remembering them all. They may have a general sense that "I should be using an *apply function here", but it can be tough to keep them all straight at fi...
How do I programmatically determine if there are uncommitted changes?
In a Makefile, I'd like to perform certain actions if there are uncommitted changes (either in the working tree or the index). What's the cleanest and most efficient way to do that? A command that exits with a return value of zero in one case and non-zero in the other would suit my purposes.
...
Try catch statements in C
...tjmp and longjmp calls.
static jmp_buf s_jumpBuffer;
void Example() {
if (setjmp(s_jumpBuffer)) {
// The longjmp was executed and returned control here
printf("Exception happened here\n");
} else {
// Normal code execution starts here
Test();
}
}
void Test() {
// Rough eq...
Split by comma and strip whitespace in Python
...of the blank list entries. > text = [x.strip() for x in text.split('.') if x != '']
– RandallShanePhD
Jul 28 '17 at 19:41
...
Array Size (Length) in C#
...
If it's a one-dimensional array a,
a.Length
will give the number of elements of a.
If b is a rectangular multi-dimensional array (for example, int[,] b = new int[3, 5];)
b.Rank
will give the number of dimensions (2) an...