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How can I check whether a option already exist in select by JQuery
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341
This evaluates to true if it already exists:
$("#yourSelect option[value='yourValue']").length ...
Is a Java hashmap search really O(1)?
I've seen some interesting claims on SO re Java hashmaps and their O(1) lookup time. Can someone explain why this is so? Unless these hashmaps are vastly different from any of the hashing algorithms I was bought up on, there must always exist a dataset that contains collisions.
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Closing multiple issues in Github with a commit message
I know you can close issues by putting closes #1 or fixes #1 in the commit message. What is the best way to close multiple issues in the same commit message?
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How do I check the difference, in seconds, between two dates?
...es, use total_seconds like this:
import datetime as dt
a = dt.datetime(2013,12,30,23,59,59)
b = dt.datetime(2013,12,31,23,59,59)
(b-a).total_seconds()
86400.0
#note that seconds doesn't give you what you want:
(b-a).seconds
0
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Iterating over each line of ls -l output
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Set IFS to newline, like this:
IFS='
'
for x in `ls -l $1`; do echo $x; done
Put a sub-shell around it if you don't want to set IFS permanently:
(IFS='
'
for x in `ls -l $1`; do echo $x; done)
Or use while | read instead:
ls -l $1 | while read x; do echo $x; done
One more ...
Detect iPad users using jQuery?
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317
iPad Detection
You should be able to detect an iPad user by taking a look at the userAgent pro...
cocktail party algorithm SVD implementation … in one line of code?
...mentation is http://www.cs.nyu.edu/~roweis/kica.html
ok, here's code -
[x1, Fs1] = audioread('mix1.wav');
[x2, Fs2] = audioread('mix2.wav');
xx = [x1, x2]';
yy = sqrtm(inv(cov(xx')))*(xx-repmat(mean(xx,2),1,size(xx,2)));
[W,s,v] = svd((repmat(sum(yy.*yy,1),size(yy,1),1).*yy)*yy');
a = W*xx; %W is...
What's the difference between lists and tuples?
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1032
Apart from tuples being immutable there is also a semantic distinction that should guide thei...
Check if database exists in PostgreSQL using shell
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