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Rails 4 multiple image or file upload using carrierwave
... do not prevent the post model from saving. Instead the post is saved, and then the ActiveRecord invalid error is thrown for the attachment model only. I think this is because of the create! method. but using create instead just fails silently. Any idea how to have the validation happen on the post ...
How to represent empty char in Java Character class
...e a character without leaving a space".
If you are dealing with a char[], then you would create a new char[] with that element removed.
If you are dealing with a String, then you would create a new String (String is immutable) with the character removed.
Here are some samples of how you could rem...
Speed up the loop operation in R
... conditional cumsum
if you know that in your data max sequence isn't large then you can change loop to vectorized while, something like
while (any(cond)) {
indx <- c(FALSE, cond[-1] & !cond[-n])
res[indx] <- res[indx] + res[which(indx)-1]
cond[indx] <- FALSE
}
Code use...
Performance of Java matrix math libraries? [closed]
...libraries didn't perform too well. However if someone has to code in Java, then the best option is JBLAS. Jama, Colt and Parallel Colt are not fast.
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Is there a built in function for string natural sort?
...lm2, Elm2, elm2] as [elm1, Elm2, elm2, elm2] reliably (caps before lower), then you can simply call natural_sort(sorted(lst)). More inefficient, but very easy to get a repeatable sort. Compile the regex for a ~50% speedup. as seen in Claudiu's answer.
– Charlie Haley
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How do you use an identity file with rsync?
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If you're using csh style shell (such as fish) then do eval (ssh-agent -c)
– Dave
Dec 29 '16 at 13:14
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What is a plain English explanation of “Big O” notation?
...digit numbers, if one of them has 4 digits and the other one has 6 digits, then we only have 24 multiplications. Still, we calculate the worst case scenario for that 'n', i.e when both are 6 digit numbers. Hence Big-O notation is about the Worst-case scenario of an algorithm.
The Telephone Book
The ...
How to create a bash script to check the SSH connection?
... ConnectTimeout=5 user@host echo ok 2>&1)
if [[ $status == ok ]] ; then
echo auth ok, do something
elif [[ $status == "Permission denied"* ]] ; then
echo no_auth
else
echo other_error
fi
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Screenshot Apps for iPhone simulator [closed]
...better and faster!
You can also try cmd+ctrl+C while in the iOS simulator. Then open Preview or an image editing program and try cmd+N (the image is in the clipboard).
Edit: According to apple's new guidelines we need to provide high resolution screenshots. For that go to Simulator->Hardware->...
Is a Java hashmap search really O(1)?
...Even O(n/10^100) is still O(n). I get your point about efficiency bringing then ratio down but that still puts the algorithm at O(n).
– paxdiablo
Jun 28 '09 at 16:59
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