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Why were pandas merges in python faster than data.table merges in R in 2012?
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It looks like Wes may have discovered a known issue in data.table when the number of unique strings (levels) is large: 10,000.
Does Rprof() reveal most of the time spent in the call sortedmatch(levels(i[[lc]]), levels(x[[rc]])? This isn't really the join itself (t...
Get the current year in JavaScript
...which you can use as per the requirements, some functions are as,
var now = new Date()
console.log("Current Time is: " + now);
// getFullYear function will give current year
var currentYear = now.getFullYear()
console.log("Current year is: " + currentYear);
// getYear will give you th...
Is git's semi-secret empty tree object reliable, and why is there not a symbolic name for it?
Git has a well-known, or at least sort-of-well-known, empty tree whose SHA1 is:
3 Answers
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Using the Swift if let with logical AND operator &&
We know that we can use an if let statement as a shorthand to check for an optional nil then unwrap.
6 Answers
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RAII and smart pointers in C++
... should be anyway), closing the file is taken care of for us. So, our code now looks something like:
File file("/path/to/file");
// Do stuff with file
// No need to close it - destructor will do that for us
This cannot be done in Java since there's no guarantee when the object will be destroyed, ...
JavaScript get clipboard data on paste event (Cross browser)
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The situation has changed since writing this answer: now that Firefox has added support in version 22, all major browsers now support accessing the clipboard data in a paste event. See Nico Burns's answer for an example.
In the past this was not generally possible in a cross-b...
Error in finding last used cell in Excel with VBA
... It is highly unreliable. Try this experiment.
Type something in cell A5. Now when you calculate the last row with any of the methods given below, it will give you 5. Now color the cell A10 red. If you now use the any of the below code, you will still get 5. If you use Usedrange.Rows.Count what do ...
Does Foreign Key improve query performance?
...pretty much useless because it doesn't answer the question. It's great to know that foreign keys are not intended to have a (positive) effect on performance, but the question was concerning reality, not intentions.
– John
Mar 15 '17 at 16:04
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When restoring a backup, how do I disconnect all active connections?
...nd select 'Activity Monitor'.
When this opens, expand the Processes group.
Now use the drop-down to filter the results by database name.
Kill off the server connections by selecting the right-click 'Kill Process' option.
sh...
Const in JavaScript: when to use it and is it necessary?
...eginning of 2014 and a lot has changed since then. ecmascript-6 support is now the norm. All modern browsers now support const so it should be pretty safe to use without any problems.
Original Answer from 2014
Despite having fairly decent browser support, I'd avoid using it for now. From MDN's a...