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Remove the last line from a file in Bash
...th (length of file minus length of length of its last line, using bc) and, set that position to be the end of the file (by dding one byte of /dev/null onto it).
This is fast because tail starts reading from the end, and dd will overwrite the file in place rather than copy (and parse) every line o...
Standard deviation of a list
...ta list.
Sample std: You need to pass ddof (i.e. Delta Degrees of Freedom) set to 1, as in the following example:
numpy.std(< your-list >, ddof=1)
The divisor used in calculations is N - ddof, where N represents the number of elements. By default ddof is zero.
It calculates sampl...
Preferred method to store PHP arrays (json_encode vs serialize)
...k of at the moment.
A simple speed test to compare the two
<?php
ini_set('display_errors', 1);
error_reporting(E_ALL);
// Make a big, honkin test array
// You may need to adjust this depth to avoid memory limit errors
$testArray = fillArray(0, 5);
// Time json encoding
$start = microtime(tru...
Base64 encoding and decoding in client-side Javascript
...
Some browsers such as Firefox, Chrome, Safari, Opera and IE10+ can handle Base64 natively. Take a look at this Stackoverflow question. It's using btoa() and atob() functions.
For server-side JavaScript (Node), you can use Buffers to decode.
If y...
从源代码剖析Mahout推荐引擎 - 大数据 & AI - 清泛网 - 专注C/C++及内核技术
从源代码剖析Mahout推荐引擎前言Mahout框架中cf.taste包实现了推荐算法引擎，它提供了一套完整的推荐算法工具集，同时规范了数据结构，并标准化了程序开发过程。应用推...前言
Mahout框架中cf.taste包实现了推荐算法引擎，它提供...
Why can't my program compile under Windows 7 in French? [closed]
... You can get your proc back however with this (French) Windows 7 command:
set max-working-hours-a-week = 35
Repeat when you're stuck (but don't forget to lower the number each time!).
share
...
How to print a string in fixed width?
...n't shorten strings above 20 characters however. Use '%(name)20.20s' which sets 20 both as min and max string length!
– xjcl
Feb 21 at 21:44
add a comment
|...
How to see top processes sorted by actual memory usage?
I have a server with 12G of memory. A fragment of top is shown below:
12 Answers
12
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How does the MapReduce sort algorithm work?
...
Just guessing...
Given a huge set of data, you would partition the data into some chunks to be processed in parallel (perhaps by record number i.e. record 1 - 1000 = partition 1, and so on).
Assign / schedule each partition to a particular node in the cl...
Python: Find in list
... whether something is a member of your list, you can convert the list to a set first and take advantage of constant time set lookup:
my_set = set(my_list)
if item in my_set: # much faster on average than using a list
# do something
Not going to be the correct solution in every case, but for ...