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Convert light frequency to RGB?
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answered Sep 24 '09 at 15:47
Stephen MesaStephen Mesa
4,31333 gold badges2121 silver badges1616 bronze badges
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Understanding the Use of ColorMatrix and ColorMatrixColorFilter to Modify a Drawable's Hue
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10 Answers
10
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cartesian product in pandas
...f1, df2,on='key')[['col1', 'col2', 'col3']]
Output:
col1 col2 col3
0 1 3 5
1 1 3 6
2 2 4 5
3 2 4 6
See here for the documentation: http://pandas.pydata.org/pandas-docs/stable/merging.html#brief-primer-on-merge-methods-relational-algebra
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Regular expression that matches valid IPv6 addresses
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30 Answers
30
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What is the easiest way to remove the first character from a string?
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I kind of favor using something like:
asdf = "[12,23,987,43"
asdf[0] = ''
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|
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Validating IPv4 addresses with regexp
...tion, but without much luck. It seemed at one point I had had it with (25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?(\.|$)){4} , but it produces some strange results:
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How to find list intersection?
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answered Sep 13 '10 at 1:32
Mark ByersMark Byers
683k155155 gold badges14681468 silver badges13881388 bronze badges
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How to increase the gap between text and underlining in CSS
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370
No, but you could go with something like border-bottom: 1px solid #000 and padding-bottom: 3px.
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how does multiplication differ for NumPy Matrix vs Array classes?
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Neil G
27.5k3030 gold badges127127 silver badges228228 bronze badges
answered Oct 8 '10 at 16:49
Joe KingtonJoe Ki...
How to profile a bash shell script slow startup?
... you'd like to begin a trace in any Bash script):
PS4='+ $(date "+%s.%N")\011 '
exec 3>&2 2>/tmp/bashstart.$$.log
set -x
add
set +x
exec 2>&3 3>&-
at the end of ~/.bashrc (or at the end of the section of any Bash script you'd like tracing to stop). The \011 is an octal ...