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Why are elementwise additions much faster in separate loops than in a combined loop?
Suppose a1 , b1 , c1 , and d1 point to heap memory and my numerical code has the following core loop.
10 Answers
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What is the easiest way to remove the first character from a string?
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p asdf
# >> "12,23,987,43"
I'm always looking for the fastest and most readable way of doing things:
require 'benchmark'
N = 1_000_000
puts RUBY_VERSION
STR = "[12,23,987,43"
Benchmark.bm(7) do |b|
b.report('[0]') { N.times { "[12,23,987,43"[0] = '' } }
b.report('sub') { N.time...
Array slicing in Ruby: explanation for illogical behaviour (taken from Rubykoans.com)
I was going through the exercises in Ruby Koans and I was struck by the following Ruby quirk that I found really unexplainable:
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Most efficient way to create a zero filled JavaScript array?
...ay(len).fill(0);
Not sure if it's fast, but I like it because it's short and self-describing.
It's still not in IE (check compatibility), but there's a polyfill available.
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Getting individual colors from a color map in matplotlib
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You can do this with the code below, and the code in your question was actually very close to what you needed, all you have to do is call the cmap object you have.
import matplotlib
cmap = matplotlib.cm.get_cmap('Spectral')
rgba = cmap(0.5)
print(rgba) # (0.9...
what does -webkit-transform: translate3d(0,0,0); exactly do? Apply to body?
...rocessing unit
(GPU) to make pixels fly. Web applications, on the other hand, run in
the context of the browser, which lets the software do most (if not
all) of the rendering, resulting in less horsepower for transitions.
But the Web has been catching up, and most browser vendors now provide...
How do I replace NA values with zeros in an R dataframe?
I have a data frame and some columns have NA values.
21 Answers
21
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Looping in a spiral
...algorithm that would let him loop through the elements of an NxM matrix (N and M are odd). I came up with a solution, but I wanted to see if my fellow SO'ers could come up with a better solution.
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Fastest way to check if a string matches a regexp in ruby?
... avoids object allocations performed by other methods such as Regexp#match and =~:
Regexp#match?
Added Regexp#match?, which executes a regexp match without creating a back reference object and changing $~ to reduce object allocation.
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What is the best way to compute trending topics or tags?
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This problem calls for a z-score or standard score, which will take into account the historical average, as other people have mention, but also the standard deviation of this historical data, making it more robust than just using the average.
In your case a z-sc...