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“Cloning” row or column vectors
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Here's an elegant, Pythonic way to do it:
>>> array([[1,2,3],]*3)
array([[1, 2, 3],
[1, 2, 3],
[1, 2, 3]])
>>> array([[1,2,3],]*3).transpose()
array([[1, 1, 1],
[2, 2, 2],
[3, 3, 3]])
the problem with [16] seems to be that the transpose has ...
What does ** (double star/asterisk) and * (star/asterisk) do for parameters?
... the following method definitions, what does the * and ** do for param2 ?
22 Answers
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What does -1 mean in numpy reshape?
...inal shape'
numpy allow us to give one of new shape parameter as -1 (eg: (2,-1) or (-1,3) but not (-1, -1)). It simply means that it is an unknown dimension and we want numpy to figure it out. And numpy will figure this by looking at the 'length of the array and remaining dimensions' and making su...
Split data frame string column into multiple columns
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291
Use stringr::str_split_fixed
library(stringr)
str_split_fixed(before$type, "_and_", 2)
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Calculating sum of repeated elements in AngularJS ng-repeat
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answered Mar 29 '14 at 12:53
VamsiVamsi
8,20433 gold badges3333 silver badges4343 bronze badges
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How to convert 2D float numpy array to 2D int numpy array?
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Use the astype method.
>>> x = np.array([[1.0, 2.3], [1.3, 2.9]])
>>> x
array([[ 1. , 2.3],
[ 1.3, 2.9]])
>>> x.astype(int)
array([[1, 2],
[1, 2]])
share
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how to calculate binary search complexity
...rer as informal ones:
The question is, how many times can you divide N by 2 until you have 1? This is essentially saying, do a binary search (half the elements) until you found it. In a formula this would be this:
1 = N / 2x
multiply by 2x:
2x = N
now do the log2:
log2(2x) = l...
How to validate phone numbers using regex
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42 Answers
42
Active
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Fastest way to iterate over all the chars in a String
...(not advised), read this first: http://www.javaspecialists.eu/archive/Issue237.html
Starting from Java 9, the solution as described won't work anymore, because now Java will store strings as byte[] by default.
SECOND UPDATE: As of 2016-10-25, on my AMDx64 8core and source 1.8, there is no difference...
Programmatically obtain the Android API level of a device?
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answered Nov 2 '14 at 11:01
Arkadiusz CieślińskiArkadiusz Cieśliński
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