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What is IP address '::1'?
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::1 is the loopback address in IPv6. Think of it as the IPv6 version of 127.0.0.1.
See http:...
How to insert element into arrays at specific position?
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214
array_slice() can be used to extract parts of the array, and the union array operator (+) can r...
Fastest way to flatten / un-flatten nested JSON objects
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Reverse Range in Swift
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185
Update For latest Swift 3 (still works in Swift 4)
You can use the reversed() method on a ran...
What is the most efficient way of finding all the factors of a number in Python?
...return set(reduce(list.__add__,
([i, n//i] for i in range(1, int(n**0.5) + 1) if n % i == 0)))
This will return all of the factors, very quickly, of a number n.
Why square root as the upper limit?
sqrt(x) * sqrt(x) = x. So if the two factors are the same, they're both the square...
Regular expression for floating point numbers
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How to calculate the number of occurrence of a given character in each row of a column of strings?
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Can dplyr package be used for conditional mutating?
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Use ifelse
df %>%
mutate(g = ifelse(a == 2 | a == 5 | a == 7 | (a == 1 & b == 4), 2,
ifelse(a == 0 | a == 1 | a == 4 | a == 3 | c == 4, 3, NA)))
Added - if_else: Note that in dplyr 0.5 there is an if_else function defined so an alternative would be to replace ifelse with i...
How to determine the longest increasing subsequence using dynamic programming?
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19 Answers
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Git Tag list, display commit sha1 hashes
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146
To get git tags with the SHA1 hash of the Tag object, you can run:
git show-ref --tags
The ...