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What is the purpose of setting a key in data.table?
...e other vignettes that we plan to.
I've updated this answer again (Feb 2016) in light of the new on= feature that allows ad-hoc joins as well. See history for earlier (outdated) answers.
What exactly does setkey(DT, a, b) do?
It does two things:
reorders the rows of the data.table DT by the...
jQuery Date Picker - disable past dates
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Nicola PeluchettiNicola Peluchetti
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How to make an anchor tag refer to nothing?
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107
If you don't want to have it point to anything, you probably shouldn't be using the <a> (...
What method in the String class returns only the first N characters?
...f (string.IsNullOrEmpty(str))
return str;
return str.Substring(0, Math.Min(str.Length, maxLength));
}
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How to make an image center (vertically & horizontally) inside a bigger div [duplicate]
I have a div 200 x 200 px. I want to place a 50 x 50 px image right in the middle of the div.
36 Answers
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TypeScript type signatures for functions with variable argument counts
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210
TypeScript uses the ECMAScript 6 spread proposal,
http://wiki.ecmascript.org/doku.php?id=har...
quick random row selection in Postgres
...or(random()*N) LIMIT 1;
Consider a table of 2 rows; random()*N generates 0 <= x < 2 and for example SELECT myid FROM mytable OFFSET 1.7 LIMIT 1; returns 0 rows because of implicit rounding to nearest int.
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How to round up the result of integer division?
...age - 1) / recordsPerPage;
Source: Number Conversion, Roland Backhouse, 2001
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How do I change the color of the text in a UIPickerView under iOS 7?
... containing the UIPickerView, spaced 35 pts apart for a picker height of 180.
Swift 3:
func pickerView(_ pickerView: UIPickerView, attributedTitleForRow row: Int, forComponent component: Int) -> NSAttributedString? {
let string = "myString"
return NSAttributedString(string: string, att...
Fastest way to determine if an integer is between two integers (inclusive) with known sets of values
...e interval to the point of origin and checks if number is in the interval [0, D], where D = upper - lower. If number below lower bound: negative, and if above upper bound: larger than D.
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