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How to merge dictionaries of dictionaries?
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147
this is actually quite tricky - particularly if you want a useful error message when things ar...
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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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...
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 ...
How do I exchange keys with values in a dictionary?
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17 Answers
17
Active
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How to install lxml on Ubuntu
I'm having difficulty installing lxml with easy_install on Ubuntu 11.
11 Answers
11
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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...