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How can I quickly sum all numbers in a file?
...;
}
-e syntax OK
Just for giggles, I tried this with a file containing 1,000,000 numbers (in the range 0 - 9,999). On my Mac Pro, it returns virtually instantaneously. That's too bad, because I was hoping using mmap would be really fast, but it's just the same time:
use 5.010;
use File::Map qw(ma...
How do I include negative decimal numbers in this regular expression?
...e with positive values, but I want it to also allow negative values e.g. -10, -125.5 etc.
14 Answers
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How to check if a number is a power of 2
...his problem:
bool IsPowerOfTwo(ulong x)
{
return (x & (x - 1)) == 0;
}
Note, this function will report true for 0, which is not a power of 2. If you want to exclude that, here's how:
bool IsPowerOfTwo(ulong x)
{
return (x != 0) && ((x & (x - 1)) == 0);
}
Explanation
Fi...
How to create the most compact mapping n → isprime(n) up to a limit N?
...ent every odd number with one bit e.g. for the given range of numbers (1, 10], starts at 3: 1110
31 Answers
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Ruby on Rails and Rake problems: uninitialized constant Rake::DSL
...
A tweet from DHH earlier. Rake .9.0 breaks Rails and several other things, you need to:
gem "rake", "0.8.7"
in your Gemfile.
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improve this answer
...
Permutations in JavaScript?
...
108
If you notice, the code actually splits the chars into an array prior to do any permutation, so...
UITableView - scroll to the top
...e top. But I cannot guarantee that the first object is going to be section 0, row 0. May be that my table view will start from section number 5.
...
Sorting arrays in NumPy by column
... copy:
In [1]: import numpy as np
In [2]: a = np.array([[1,2,3],[4,5,6],[0,0,1]])
In [3]: np.sort(a.view('i8,i8,i8'), order=['f1'], axis=0).view(np.int)
Out[3]:
array([[0, 0, 1],
[1, 2, 3],
[4, 5, 6]])
To sort it in-place:
In [6]: a.view('i8,i8,i8').sort(order=['f1'], axis=0) #&...
Fast Bitmap Blur For Android SDK
... I'm looping through the pixels of an image to blur it. This takes about 30 seconds on a 640x480 image.
19 Answers
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Reading an Excel file in python using pandas
...)
Tid dummy1 dummy2 dummy3 dummy4 dummy5 \
0 2006-09-01 00:00:00 0 5.894611 0.605211 3.842871 8.265307
1 2006-09-01 01:00:00 0 5.712107 0.605211 3.416617 8.301360
2 2006-09-01 02:00:00 0 5.105300 0.605211 3.090865 8.335395
3 2006...