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data.table vs dplyr: can one do something well the other can't or does poorly?
...j and by together is by design. By keeping related operations together, it allows to easily optimise operations for speed and more importantly memory usage, and also provide some powerful features, all while maintaining the consistency in syntax.
1. Speed
Quite a few benchmarks (though mostly on g...
HTML5 Canvas 100% Width Height of Viewport?
....getContext('2d');
// resize the canvas to fill browser window dynamically
window.addEventListener('resize', resizeCanvas, false);
function resizeCanvas() {
canvas.width = window.innerWidth;
canvas.height = window.innerHeight;
/**
* You...
HTML table td meaning
...ered Sep 20 '15 at 22:27
Dbeast1_16Dbeast1_16
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Resize UIImage by keeping Aspect ratio and width
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+(UIImage*)imageWithImage: (UIImage*) sourceImage scaledToWidth: (float) i_width
{
float oldWidth = sourceImage.size.width;
float scaleFactor = i_width / oldWidth;
float newHeight = sourceImage.size.height * scaleFactor;
float newWidth = oldWidth * scaleFactor;
UIGraphicsBegin...
What does the [Flags] Enum Attribute mean in C#?
... Such collections are often used with bitwise operators, for example:
var allowedColors = MyColor.Red | MyColor.Green | MyColor.Blue;
Note that the [Flags] attribute doesn't enable this by itself - all it does is allow a nice representation by the .ToString() method:
enum Suits { Spades = 1, Clu...
Summarizing multiple columns with dplyr? [duplicate]
...
The dplyr package contains summarise_all for this aim:
library(dplyr)
df %>% group_by(grp) %>% summarise_all(list(mean))
#> # A tibble: 3 x 5
#> grp a b c d
#> <int> <dbl> <dbl> <dbl> <dbl>
#>...
JSON Stringify changes time of date because of UTC
...
thanks... I actually found a great library here, blog.stevenlevithan.com/archives/date-time-format all you need to do this (maybe it will help you) , you pass false and it doesn't convert. var something = dateFormat(myStartDate, "isoDateTi...
Random strings in Python
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In many cases, random isn't really required. Rather, all you really need is unique.
– Chase Seibert
Jan 8 '10 at 19:48
1
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void in C# generics?
...nctions need to return null, but if it unifies your code, it should be a small price to pay.
This inability to use void as a return type is at least partially responsible for a split between the Func<...> and Action<...> families of generic delegates: had it been possible to return void...
jQuery Validate - Enable validation for hidden fields
...ry, this could break an existing
setup. In the unlikely case that it actually does, you can fix it by
setting the ignore-option to “[]” (square brackets without the
quotes)."
To change this setting for all forms:
$.validator.setDefaults({
ignore: [],
// any other default option...