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What is the most efficient way of finding all the factors of a number in Python?
...(reduce(list.__add__,
([i, n//i] for i in range(1, int(n**0.5) + 1) if n % i == 0)))
This will return all of the factors, very quickly, of a number n.
Why square root as the upper limit?
sqrt(x) * sqrt(x) = x. So if the two factors are the same, they're both the square root. If ...
Find integer index of rows with NaN in pandas dataframe
...MultiIndex that you can use to index back into df, e.g.:
df['a'].ix[index[0]]
>>> 1.452354
For the integer index:
df_index = df.index.values.tolist()
[df_index.index(i) for i in index]
>>> [3, 6]
share...
pandas: How do I split text in a column into multiple rows?
...
207
+50
This spl...
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.
share
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improve this answer
...
C++ performance challenge: integer to std::string conversion
...
#include <string>
const char digit_pairs[201] = {
"00010203040506070809"
"10111213141516171819"
"20212223242526272829"
"30313233343536373839"
"40414243444546474849"
"50515253545556575859"
"60616263646566676869"
"70717273747576777879"
"80818283848586...
Calculating Pearson correlation and significance in Python
...
201
You can have a look at scipy.stats:
from pydoc import help
from scipy.stats.stats import pears...
How to change the color of an svg element?
...splay: none;
}
.no-svg .my-svg-alternate {
display: block;
width: 100px;
height: 100px;
background-image: url(image.png);
}
<svg width="96px" height="96px" viewBox="0 0 512 512" enable-background="new 0 0 512 512" xml:space="preserve">
<path id="time-3-icon" d="M256,50C142....
Which is faster: while(1) or while(2)?
...arying levels of optimization:
int main(void) {
while(1) {}
return 0;
}
int main(void) {
while(2) {}
return 0;
}
Even with no optimizations (-O0), the generated assembly was identical for both programs. Therefore, there is no speed difference between the two loops.
For reference, ...
How to insert element into arrays at specific position?
...on array operator (+) can recombine the parts.
$res = array_slice($array, 0, 3, true) +
array("my_key" => "my_value") +
array_slice($array, 3, count($array)-3, true);
This example:
$array = array(
'zero' => '0',
'one' => '1',
'two' => '2',
'three' => '3',
);
$...
Reverse Range in Swift
...:to:by:) is similar but excludes the last value
for i in stride(from:5,to:0,by:-1) { print(i) } // 5 4 3 2 1
Update For latest Swift 2
First of all, protocol extensions change how reverse is used:
for i in (1...5).reverse() { print(i) } // 5 4 3 2 1
Stride has been reworked in Xcode 7 Beta 6. ...