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Convert a row of a data frame to vector
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Might have been changed in the meantime, but today unlist allows dropping names: identical(unlist(df[1,], use.names = FALSE), as.numeric(df[1,])) (and btw df still is not a sensible name for a data.frame... ;-))
– Andri Signorell
Sep 25 '1...
Inserting string at position x of another string
...er https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/substr)
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Get the index of the object inside an array, matching a condition
...lorer, there's a polyfill on the linked page.
Performance note
Function calls are expensive, therefore with really big arrays a simple loop will perform much better than findIndex:
let test = [];
for (let i = 0; i < 1e6; i++)
test.push({prop: i});
let search = test.length - 1;...
What is the difference between attribute and property? [closed]
...roperties.
To further confuse things, changes to the properties will typically update the attributes.
For example, changing the element.href property will update the href attribute on the element, and that'll be reflected in a call to element.getAttribute('href').
However if you subsequently read...
GoogleTest: How to skip a test?
...o). I then removed my comment, figuring it's obsolete... but that's some really good info! +1
– Kiril
Aug 26 '11 at 17:05
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Fast way of counting non-zero bits in positive integer
...nt() took about 1/20th of the time of bin(n).count("1"). So if you can install gmpy, use that.
To answer a question in the comments, for bytes I'd use a lookup table. You can generate it at runtime:
counts = bytes(bin(x).count("1") for x in range(256)) # py2: use bytearray
Or just define it lit...
How do I access my SSH public key?
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cat ~/.ssh/id_rsa.pub or cat ~/.ssh/id_dsa.pub
You can list all the public keys you have by doing:
$ ls ~/.ssh/*.pub
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Django's SuspiciousOperation Invalid HTTP_HOST header
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If your ALLOWED_HOSTS is set correctly, then it is possible someone is probing your site for the vulnerability by spoofing the header.
There is discussion right now by the Django developers to change this from a 500 internal server...
Memoization in Haskell?
...tion (fix)
Let's define f, but make it use 'open recursion' rather than call itself directly.
f :: (Int -> Int) -> Int -> Int
f mf 0 = 0
f mf n = max n $ mf (n `div` 2) +
mf (n `div` 3) +
mf (n `div` 4)
You can get an unmemoized f by using fix f
This...
How can I recall the argument of the previous bash command?
Is there a way in Bash to recall the argument of the previous command?
7 Answers
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