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Which is faster in Python: x**.5 or math.sqrt(x)?
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93
math.sqrt(x) is significantly faster than x**0.5.
import math
N = 1000000
%%timeit
for i in r...
How to filter Pandas dataframe using 'in' and 'not in' like in SQL
...andas as pd
>>> df
country
0 US
1 UK
2 Germany
3 China
>>> countries_to_keep
['UK', 'China']
>>> df.country.isin(countries_to_keep)
0 False
1 True
2 False
3 True
Name: country, dtype: bool
>>> df[df.country.isin(countries_to_ke...
How do you get the magnitude of a vector in Numpy?
...ray -- say x.norm() -- but oh well).
import numpy as np
x = np.array([1,2,3,4,5])
np.linalg.norm(x)
You can also feed in an optional ord for the nth order norm you want. Say you wanted the 1-norm:
np.linalg.norm(x,ord=1)
And so on.
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Why is pow(a, d, n) so much faster than a**d % n?
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edited Jan 3 '13 at 6:08
answered Jan 3 '13 at 6:03
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The $.param( ) inverse function in JavaScript / jQuery
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answered Jun 9 '11 at 19:23
ccecce
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Markdown: continue numbered list
In the following markdown code I want item 3 to start with list number 3. But because of the code block in between markdown starts this list item as a new list. Is there any way to prevent that behaviour?
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How to delete multiple values from a vector?
...vector like: a = c(1:10) and I need to remove multiple values, like: 2, 3, 5
8 Answers
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jQuery select by attribute using AND and OR operators
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AND operation
a=$('[myc="blue"][myid="1"][myid="3"]');
OR operation, use commas
a=$('[myc="blue"],[myid="1"],[myid="3"]');
As @Vega commented:
a=$('[myc="blue"][myid="1"],[myc="blue"][myid="3"]');
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Compare two data.frames to find the rows in data.frame 1 that are not present in data.frame 2
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13 Answers
13
Active
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How to concatenate twice with the C preprocessor and expand a macro as in “arg ## _ ## MACRO”?
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Standard C Preprocessor
$ cat xx.c
#define VARIABLE 3
#define PASTER(x,y) x ## _ ## y
#define EVALUATOR(x,y) PASTER(x,y)
#define NAME(fun) EVALUATOR(fun, VARIABLE)
extern void NAME(mine)(char *x);
$ gcc -E xx.c
# 1 "xx.c"
# 1 "<built-in>"
# 1 "<command-line>"
# 1...