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Is there a short contains function for lists?
...myItem not in list:
# do something
It's work fine for lists, tuples, sets and dicts (check keys).
Note that this is an O(n) operation in lists and tuples, but an O(1) operation in sets and dicts.
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Numpy: find first index of value fast
How can I find the index of the first occurrence of a number in a Numpy array?
Speed is important to me. I am not interested in the following answers because they scan the whole array and don't stop when they find the first occurrence:
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string.IsNullOrEmpty(string) vs. string.IsNullOrWhiteSpace(string)
Is use of string.IsNullOrEmpty(string) when checking a string considered as bad practice when there is string.IsNullOrWhiteSpace(string) in .NET 4.0 and above?
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C default arguments
...per function, and a macro
around the wrapper function. In my work I have a set of macros to automate all this; once
you understand the flow it'll be easy for you to do the same.
I've written this up elsewhere, so here's a detailed external link to supplement the summary here: http://modelingwithdat...
How to disallow temporaries
...too.
Any constructor you want to guard needs a default argument on which set(guard) is called.
struct Guard {
Guard()
:guardflagp()
{ }
~Guard() {
assert(guardflagp && "Forgot to call guard?");
*guardflagp = 0;
}
void *set(Guard const *&guardflag) {
if(guar...
Reduce, fold or scan (Left/Right)?
... editor after snippets, if snippets enabled
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JavaScript + Unicode regexes
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Unicode's website provides a way to translate Unicode categories into a set of code points. Since it's Unicode's website, the information from it should be accurate.
Note that you will need to exclude the high-end characters, as JavaScript can only handle characters less than FFFF (hex). I sugge...
What are free monads?
...m a Y to an X without gaining anything extra.
Examples: a monoid (X) is a set (Y) with extra structure (P) that basically says it has an operation (you can think of addition) and some identity (like zero).
So
class Monoid m where
mempty :: m
mappend :: m -> m -> m
Now, we all know ...
Split (explode) pandas dataframe string entry to separate rows
...lit(','))
for _, row in a.iterrows()]).reset_index()
Out[55]:
index 0
0 a 1
1 b 1
2 c 1
3 d 2
4 e 2
5 f 2
Then you just have to rename the columns
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PostgreSQL: How to pass parameters from command line?
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Sure, just use \set v3 'another value'. Just remember, when you need to quote the value in SQL statement, use apostrophes around variable name, like this: SELECT * FROM foo WHERE bar = :'v3';
– Cromax
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