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How do you extract a column from a multi-dimensional array?
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>>> import numpy as np
>>> A = np.array([[1,2,3,4],[5,6,7,8]])
>>> A
array([[1, 2, 3, 4],
[5, 6, 7, 8]])
>>> A[:,2] # returns the third columm
array([3, 7])
See also: "numpy.arange" and "reshape" to allocate memory
Example: (Allocating a array with sha...
Hash and salt passwords in C#
...Hash(byte[] plainText, byte[] salt)
{
HashAlgorithm algorithm = new SHA256Managed();
byte[] plainTextWithSaltBytes =
new byte[plainText.Length + salt.Length];
for (int i = 0; i < plainText.Length; i++)
{
plainTextWithSaltBytes[i] = plainText[i];
}
for (int i = 0; i < sal...
How to format strings in Java
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edited Jun 24 '11 at 16:54
answered Jun 21 '11 at 21:18
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C# constructor execution order
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howcheng
1,46911 gold badge99 silver badges1515 bronze badges
answered Dec 10 '09 at 17:53
Jon SkeetJon Skeet
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Cleaning `Inf` values from an R dataframe
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Timings
# some `big(ish)` data
dat <- data.frame(a = rep(c(1,Inf), 1e6), b = rep(c(Inf,2), 1e6),
c = rep(c('a','b'),1e6),d = rep(c(1,Inf), 1e6),
e = rep(c(Inf,2), 1e6))
# create data.table
library(data.table)
DT <- data.table(dat)
# replace (@mnel)
sy...
How to sort git tags by version string order of form rc-X.Y.Z.W?
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161
Use version sort
git tag -l | sort -V
or for git version >= 2.0
git tag -l --sort=v:refn...
What's the opposite of chr() in Ruby?
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If String#ord didn't exist in 1.9, it does in 2.0:
"A".ord #=> 65
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App Inventor 2 视频播放器教程 - VideoPlayer组件与WebView嵌入播放 · App Inventor 2 中文网
.navbar .nav-link .mdi, .navbar .dropdown-item .mdi { margin-right: 6px; opacity: .7; } 创建 Apps 文档 文档首页 内置块参考文档 组件参考文档 拓展参考文档 概念参考文档 IoT 参考文档 技术和其他指...
How to create index in Entity Framework 6.2 with code first
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Well 26.10.2017 Entity Framework 6.2 was officially released.
It includes a possibility to define indexes with ease via Fluent API. Ho it is to use was already announced in the beta of 6.2.
Now you can use the HasIndex() method, f...
Interview question: Check if one string is a rotation of other string [closed]
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