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Insert an element at a specific index in a list and return the updated list
...] + a[index:].
However, another way is:
a = [1, 2, 4]
b = a[:]
b.insert(2, 3)
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Difference between numpy.array shape (R, 1) and (R,)
...ers:
>>> a = numpy.arange(12)
>>> a
array([ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11])
Then a consists of a data buffer, arranged something like this:
┌────┬────┬────┬────┬────┬────┬────┬────...
Assign multiple columns using := in data.table, by group
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This now works in v1.8.3 on R-Forge. Thanks for highlighting it!
x <- data.table(a = 1:3, b = 1:6)
f <- function(x) {list("hi", "hello")}
x[ , c("col1", "col2") := f(), by = a][]
# a b col1 col2
# 1: 1 1 hi hello
# 2: 2 2 hi hello
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Reshape three column data frame to matrix (“long” to “wide” format) [duplicate]
...similar questions scattered around this site.
tmp <- data.frame(x=gl(2,3, labels=letters[24:25]),
y=gl(3,1,6, labels=letters[1:3]),
z=c(1,2,3,3,3,2))
Using the tidyverse:
The new cool new way to do this is with pivot_wider from tidyr 1.0.0. It returns a d...
Why does Math.Round(2.5) return 2 instead of 3?
...ounding)
Round(Double) / Round(Double, MidpointRounding)
Round(Decimal, Int32) / Round(Decimal, Int32, MidpointRounding)
Round(Double, Int32) / Round(Double, Int32, MidpointRounding)
Whether this default was well chosen or not is a different matter. (MidpointRounding was only introduced in .NET 2....
All combinations of a list of lists
...d itertools.product:
>>> import itertools
>>> a = [[1,2,3],[4,5,6],[7,8,9,10]]
>>> list(itertools.product(*a))
[(1, 4, 7), (1, 4, 8), (1, 4, 9), (1, 4, 10), (1, 5, 7), (1, 5, 8), (1, 5, 9), (1, 5, 10), (1, 6, 7), (1, 6, 8), (1, 6, 9), (1, 6, 10), (2, 4, 7), (2, 4, 8), (2,...
StringIO in Python3
I am using Python 3.2.1 and I can't import the StringIO module. I use
io.StringIO and it works, but I can't use it with numpy 's genfromtxt like this:
...
Get the cartesian product of a series of lists?
...
13 Answers
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What does ** (double star/asterisk) and * (star/asterisk) do for parameters?
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The *args and **kwargs is a common idiom to allow arbitrary number of arguments to functions a...