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Bash/sh - difference between && and ;
I normally use ; to combine more than one command in a line, but some people prefer && . Is there any difference? For example, cd ~; cd - and cd ~ && cd - seems to make the same thing. What version is more portable, e.g. will be supported by a bash-subset like Android's shell ...
What is the meaning of prepended double colon “::”?
...wered Nov 24 '10 at 16:27
Wyatt AndersonWyatt Anderson
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Most efficient method to groupby on an array of objects
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Here is one that outputs array and not object: groupByArray(xs, key) { return xs.reduce(function (rv, x) { let v = key instanceof Function ? key(x) : x[key]; let el = rv.find((r) => r && r.key === v); ...
Fastest hash for non-cryptographic uses?
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CRC32 is pretty fast and there's a function for it: http://www.php.net/manual/en/function.crc32.php
But you should be aware that CRC32 will have more collisions than MD5 or even SHA-1 hashes, simply because of the reduced length (32 bits compare...
Round a Floating Point Number Down to the Nearest Integer?
As the title suggests, I want to take a floating point number and round it down to the nearest integer. However, if it's not a whole, I ALWAYS want to round down the variable, regardless of how close it is to the next integer up. Is there a way to do this?
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Change text color of one word in a TextView
... answered Aug 28 '11 at 15:50
DanDan
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What does “S3 methods” mean in R?
Since I am fairly new to R, I do not know what the S3 methods and objects are. I found that there are S3 and S4 object systems, and some recommend to use S3 over S4 if possible (See Google's R Style Guide at http://google-styleguide.googlecode.com/svn/trunk/google-r-style.html )*. However, I do not...
JavaScript property access: dot notation vs. brackets?
Other than the obvious fact that the first form could use a variable and not just a string literal, is there any reason to use one over the other, and if so under which cases?
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How to print a number with commas as thousands separators in JavaScript
I am trying to print an integer in JavaScript with commas as thousands separators. For example, I want to show the number 1234567 as "1,234,567". How would I go about doing this?
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How to add an extra column to a NumPy array
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I think a more straightforward solution and faster to boot is to do the following:
import numpy as np
N = 10
a = np.random.rand(N,N)
b = np.zeros((N,N+1))
b[:,:-1] = a
And timings:
In [23]: N = 10
In [24]: a = np.random.rand(N,N)
In [25]: %timeit b = np.hstac...