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How does zip(*[iter(s)]*n) work in Python?
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111
iter() is an iterator over a sequence. [x] * n produces a list containing n quantity of x, i.e...
Selecting pandas column by location
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155
Two approaches that come to mind:
>>> df
A B C D
0...
How do you get the magnitude of a vector in Numpy?
... only one obvious way to do it", how do you get the magnitude of a vector (1D array) in Numpy?
6 Answers
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Emulate ggplot2 default color palette
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It is just equally spaced hues around the color wheel, starting from 15:
gg_color_hue <- function(n) {
hues = seq(15, 375, length = n + 1)
hcl(h = hues, l = 65, c = 100)[1:n]
}
For example:
n = 4
cols = gg_color_hue(n)
dev.new(width = 4, height = 4)
plot(1:n, pch = 16, cex = 2, col...
How to add a new row to an empty numpy array
...4)
Then be sure to append along axis 0:
arr = np.append(arr, np.array([[1,2,3]]), axis=0)
arr = np.append(arr, np.array([[4,5,6]]), axis=0)
But, @jonrsharpe is right. In fact, if you're going to be appending in a loop, it would be much faster to append to a list as in your first example, then ...
What's the difference between RANK() and DENSE_RANK() functions in oracle?
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10 Answers
10
Active
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Does the ternary operator exist in R?
... returns the latest evaluation, if-else is equivalent to ?:.
> a <- 1
> x <- if(a==1) 1 else 2
> x
[1] 1
> x <- if(a==2) 1 else 2
> x
[1] 2
The power of R is vectorization. The vectorization of the ternary operator is ifelse:
> a <- c(1, 2, 1)
> x <- ifelse(a=...
Sort rows in data.table in decreasing order on string key `order(-x,v)` gives error on data.table 1.
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147
Update
data.table v1.9.6+ now supports OP's original attempt and the following answer is no lo...