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What's the simplest way to test whether a number is a power of 2 in C++?
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190
(n & (n - 1)) == 0 is best. However, note that it will incorrectly return true for n=0, so i...
CSS Box Shadow Bottom Only [duplicate]
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Do this:
box-shadow: 0 4px 2px -2px gray;
It's actually much simpler, whatever you set the blur to (3rd value), set the spread (4th value) to the negative of it.
share
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Permutations in JavaScript?
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108
If you notice, the code actually splits the chars into an array prior to do any permutation, so...
Finding sum of elements in Swift array
...d.
Swift 3 and Swift 4:
let multiples = [...]
let sum = multiples.reduce(0, +)
print("Sum of Array is : ", sum)
Swift 2:
let multiples = [...]
sum = multiples.reduce(0, combine: +)
Some more info:
This uses Array's reduce method (documentation here), which allows you to "reduce a collectio...
Removing leading zeroes from a field in a SQL statement
...ve the leading zeroes from a particular field, which is a simple VARCHAR(10) field. So, for example, if the field contains '00001A', the SELECT statement needs to return the data as '1A'.
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Dynamically select data frame columns using $ and a character value
...itten as
`$`(df , V1)
or indeed
`$`(df , "V1")
But...
`$`(df , paste0("V1") )
...for instance will never work, nor will anything else that must first be evaluated in the second argument. You may only pass a string which is never evaluated.
Instead use [ (or [[ if you want to extract only...
Inline labels in Matplotlib
...e(np.int32)
# mask stuff outside plot
mask = (xy[:,0] >= 0) & (xy[:,0] < N) & (xy[:,1] >= 0) & (xy[:,1] < N)
xy = xy[mask]
# add to pop
for p in xy:
pop[l][tuple(p)] = 1.0
# find whitespace, nice place for label...
Why does the order of the loops affect performance when iterating over a 2D array?
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605
As others have said, the issue is the store to the memory location in the array: x[i][j]. Here'...
What is the bower (and npm) version syntax?
...ke any subsequent patch-level changes on the 1.2.x tree, starting with 1.2.0, but less than 1.3.0, you could use:
"angular": "~1.2"
or:
"angular": "~1.2.0"
This also gets you the same results as using the .x syntax:
"angular": "1.2.x"
But, you can use the tilde/~ syntax to be even more spec...
How to find all combinations of coins when given some dollar value
...r any other convenient computer algebra system) to compute the answer for 10^10^6 dollars in a couple seconds in three lines of code.
(And this was long enough ago that that’s a couple of seconds on a 75Mhz Pentium...)
sh...