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Assign multiple columns using := in data.table, by group
What is the best way to assign to multiple columns using data.table ? For example:
2 Answers
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Python multiprocessing PicklingError: Can't pickle
...you're processing a ton of stuff in python userspace this might not be the best method.
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HTML table headers always visible at top of window when viewing a large table
...o 2 tables, one for the header and one for the body. It's probably not the best approach ever but here goes:
<html>
<head>
<title>oh hai</title>
</head>
<body>
<table id="tableHeader">
<tr>
<th style="width:10...
jQuery deferreds and promises - .then() vs .done()
...ed as the argument for the function in the next step. That's why .done is best thought of as a "tap"-> it's not actually part of the composition, just something that sneaks a look at the value at a certain step and runs a function at that value, but doesn't actually alter the composition in any ...
Set cURL to use local virtual hosts
...wer and also evaluate answers based on their timestamps will never get the best help...
– Bruno
Oct 26 '14 at 14:36
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What is the fastest way to get the value of π?
...hough it's been a while since I last used it).
The time-complexity of the best algorithms is in O(M(n)log(n)), where M(n) is the time-complexity for the multiplication of two n-bit integers (M(n)=O(n log(n) log(log(n))) using FFT-based algorithms, which are usually needed when computing digits of \...
Why does C# not provide the C++ style 'friend' keyword? [closed]
...O question (asked by monoxide and linked above?. I'd be interested in how best to solve that in C#?
– Ash
Oct 15 '08 at 3:44
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How do you create a random string that's suitable for a session ID in PostgreSQL?
...he unrecoverable read error rate of drives is 1 bit per 1018 bits read, at best, while the file would contain about 1020 bits, just reading the file once from end to end would result, at least, in about 100 times more mis-read UUIDs than duplicates. Storage, network, power, and other hardware and so...
What is the definition of “interface” in object oriented programming
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To me an interface is a blueprint of a class, is this the best definition?
No. A blueprint typically includes the internals. But a interface is purely about what is visible on the outside of a class ... or more accurately, a family of classes that implement the interface.
The i...
Create Django model or update if exists
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SomeModel.objects.create(bar=the_bar, foo=100)
This will at best only run the first update-query, and only if it matched zero rows run another INSERT-query. Which will greatly increase your performance if you expect most of the rows to actually be existing.
It all comes down to your ...