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Get index of array element faster than O(n)
... Hash[array.map.with_index.to_a] # => {"a"=>0, "b"=>1, "c"=>2}
hash['b'] # => 1
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Print a list in reverse order with range()?
...rameters. range(start, stop, step)
For example, to generate a list [5,4,3,2,1,0], you can use the following:
range(5, -1, -1)
It may be less intuitive but as the comments mention, this is more efficient and the right usage of range for reversed list.
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How can I include a YAML file inside another?
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jameshfisherjameshfisher
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How to iterate over a JavaScript object?
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edited Nov 3 '19 at 12:50
Beachhouse
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What is the source code of the “this” module doing?
...is is called rot13 encoding:
d = {}
for c in (65, 97):
for i in range(26):
d[chr(i+c)] = chr((i+13) % 26 + c)
Builds the translation table, for both uppercase (this is what 65 is for) and lowercase (this is what 97 is for) chars.
print "".join([d.get(c, c) for c in s])
Prints the t...
How to get the first column of a pandas DataFrame as a Series?
...>>> import pandas as pd
>>> df = pd.DataFrame({'x' : [1, 2, 3, 4], 'y' : [4, 5, 6, 7]})
>>> df
x y
0 1 4
1 2 5
2 3 6
3 4 7
>>> s = df.ix[:,0]
>>> type(s)
<class 'pandas.core.series.Series'>
>>>
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Grep characters before and after match?
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3 characters before and 4 characters after
$> echo "some123_string_and_another" | grep -o -P '.{0,3}string.{0,4}'
23_string_and
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Logical XOR operator in C++?
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answered Oct 20 '09 at 19:03
Greg HewgillGreg Hewgill
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C++常用排序算法汇总 - C/C++ - 清泛网 - 专注C/C++及内核技术
...****************************
* 简单选择排序
* 稳定排序，O{n^2} ~ O{n^2}
* 从首位开始，循环一次找出一个比首位小的值，交换
*
* https://www.tsingfun.com
************************************/
#include<stdio.h>
#include<stdlib.h>
/*
第一种形式的选...
Peak-finding algorithm for Python/SciPy
... matplotlib.pyplot as plt
from scipy.signal import find_peaks
x = np.sin(2*np.pi*(2**np.linspace(2,10,1000))*np.arange(1000)/48000) + np.random.normal(0, 1, 1000) * 0.15
peaks, _ = find_peaks(x, distance=20)
peaks2, _ = find_peaks(x, prominence=1) # BEST!
peaks3, _ = find_peaks(x, width=20)
p...