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How to navigate through a vector using iterators? (C++)
...o move an iterator forward n spaces is not to write your own loop, but to call std::advance(it, n). It's defined to do exactly what you want, and it will automatically use it + n if the iterator is tagged as random-access, or do the loop if it has to.
– Steve Jessop
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Apply multiple functions to multiple groupby columns
...ion.
I recommend making a single custom function that returns a Series of all the aggregations. Use the Series index as labels for the new columns:
def f(x):
d = {}
d['a_sum'] = x['a'].sum()
d['a_max'] = x['a'].max()
d['b_mean'] = x['b'].mean()
d['c_d_prodsum'] = (x['c'] * x['d...
How to work with complex numbers in C?
...h:
creal(z1): get the real part (for float crealf(z1), for long double creall(z1))
cimag(z1): get the imaginary part (for float cimagf(z1), for long double cimagl(z1))
Another important point to remember when working with complex numbers is that functions like cos(), exp() and sqrt() must be repl...
Truncating long strings with CSS: feasible yet?
... cross browser CSS solution. It does come with the downside however of not allowing the text to be selected in Firefox. Check out his guest post on Matt Snider's blog for the full details on how this works.
Note this technique also prevents updating the content of the node in JavaScript using the i...
The written versions of the logical operators
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I personally think they are much better... but then I am Python biased. I don't know why some people thing that if it's not garbled it's not code...
– Matthieu M.
Mar 4 '10 at 8:28
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Check if an element's content is overflowing?
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The element may be overflown vertically, horizontally or both. This function will return you a boolean value if the DOM element is overflown:
function isOverflown(element) {
return element.scrollHeight > element.clientHeight || element.scrollWidth > e...
How to overcome TypeError: unhashable type: 'list'
...used to compare dictionary keys during a dictionary lookup quickly.
Internally, hash() method calls __hash__() method of an object which are set by default for any object.
Converting a nested list to a set
>>> a = [1,2,3,4,[5,6,7],8,9]
>>> set(a)
Traceback (most recent call last...
CSS filter: make color image with transparency white
...jP.gif" class="filter" />
</p>
First, brightness(0) makes all image black, except transparent parts, which remain transparent.
Then, invert(1) makes the black parts white.
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Why doesn't GCC optimize a*a*a*a*a*a to (a*a*a)*(a*a*a)?
...scientific application. One thing I noticed is that GCC will optimize the call pow(a,2) by compiling it into a*a , but the call pow(a,6) is not optimized and will actually call the library function pow , which greatly slows down the performance. (In contrast, Intel C++ Compiler , executable ...
Python extending with - using super() Python 3 vs Python 2
Originally I wanted to ask this question , but then I found it was already thought of before...
5 Answers
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