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Is returning by rvalue reference more efficient?
... I had always assumed the dangling reference problem went away automagically when the return type was an r-value reference. Glad I got that straighted out before it bit me. Stack smashing bugs suck.
– deft_code
Jul 15 '09 at 3:03
...
Semicolons superfluous at the end of a line in shell scripts?
...e superfluous, since the newline is also a command separator. case specifically needs double semicolons at the end of the last command in each pattern block; see help case for details.
share
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impro...
How to sort with lambda in Python
...
Use
a = sorted(a, key=lambda x: x.modified, reverse=True)
# ^^^^
On Python 2.x, the sorted function takes its arguments in this order:
sorted(iterable, cmp=None, key=None, reverse=False)
so without the key=, the function you pass in will be consi...
How do I properly escape quotes inside HTML attributes?
...ric html entities over named entities, in that named entities do not cover all characters, while numeric entities do. The full HTML4 list is at w3.org/TR/html4/sgml/entities.html .
– atk
Oct 25 '10 at 14:42
...
Do Java arrays have a maximum size?
...ry easy to test.
In a recent HotSpot VM, the correct answer is Integer.MAX_VALUE - 5. Once you go beyond that:
public class Foo {
public static void main(String[] args) {
Object[] array = new Object[Integer.MAX_VALUE - 4];
}
}
You get:
Exception in thread "main" java.lang.OutOfMemoryEr...
PostgreSQL Autoincrement
...other integer data type, such as smallint.
Example :
CREATE SEQUENCE user_id_seq;
CREATE TABLE user (
user_id smallint NOT NULL DEFAULT nextval('user_id_seq')
);
ALTER SEQUENCE user_id_seq OWNED BY user.user_id;
Better to use your own data type, rather than user serial data type.
...
Moving average or running mean
...
UPD: more efficient solutions have been proposed by Alleo and jasaarim.
You can use np.convolve for that:
np.convolve(x, np.ones((N,))/N, mode='valid')
Explanation
The running mean is a case of the mathematical operation of convolution. For the running mean, you slide...
Find integer index of rows with NaN in pandas dataframe
...
And just in case, if you want to find the coordinates of 'nan' for all the columns instead (supposing they are all numericals), here you go:
df = pd.DataFrame([[0,1,3,4,np.nan,2],[3,5,6,np.nan,3,3]])
df
0 1 2 3 4 5
0 0 1 3 4.0 NaN 2
1 3 5 6 NaN 3.0 3
np.where(np.as...
How to fix Python indentation
...py script that you find in the Tools/scripts/ directory of your Python installation:
Change Python (.py) files to use
4-space indents and no hard tab
characters. Also trim excess spaces
and tabs from ends of lines, and
remove empty lines at the end of
files. Also ensure the last line ...
.htaccess: Invalid command 'RewriteEngine', perhaps misspelled or defined by a module not included i
I have this error when trying to browse php files locally
8 Answers
8
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