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Difference between numpy.array shape (R, 1) and (R,)
In numpy , some of the operations return in shape (R, 1) but some return (R,) . This will make matrix multiplication more tedious since explicit reshape is required. For example, given a matrix M , if we want to do numpy.dot(M[:,0], numpy.ones((1, R))) where R is the number of rows (of co...
Context switches much slower in new linux kernels
We are looking to upgrade the OS on our servers from Ubuntu 10.04 LTS to Ubuntu 12.04 LTS. Unfortunately, it seems that the latency to run a thread that has become runnable has significantly increased from the 2.6 kernel to the 3.2 kernel. In fact the latency numbers we are getting are hard to belie...
Automatically expanding an R factor into a collection of 1/0 indicator variables for every factor le
...level, there is an associated column in a new data frame, which contains a 1/0 indicator. E.g., suppose I have:
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What is the easiest way to remove the first character from a string?
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15 Answers
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Understanding the Use of ColorMatrix and ColorMatrixColorFilter to Modify a Drawable's Hue
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Adding a column to a data.frame
... below. I want to add a column that classifies my data according to column 1 ( h_no ) in that way that the first series of h_no 1,2,3,4 is class 1, the second series of h_no (1 to 7) is class 2 etc. such as indicated in the last column.
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二进制组件使用指导 · App Inventor 2 中文网
...对一下就知道做对没有。
先懂三件事
1. 字节列表：一串字节就是由 0~255 的数字组成的普通列表，[165, 1, 255]。
列表积木都能用：求长度、取第几个（从 1 数起）、追加。
2. 十六进制：协议文档里的 A5 01 FF 和...
Big-O summary for Java Collections Framework implementations? [closed]
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150
This website is pretty good but not specific to Java: http://bigocheatsheet.com/
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Regular expression to match standard 10 digit phone number
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^(\+\d{1,2}\s)?\(?\d{3}\)?[\s.-]\d{3}[\s.-]\d{4}$
Matches the following
123-456-7890
(123) 4...