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How do I use floating-point division in bash?
...d
– Nahuel Fouilleul
Oct 4 '12 at 7:32
4
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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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What's the difference between tilde(~) and caret(^) in package.json?
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4053
See the NPM docs and semver docs:
~version “Approximately equivalent to version”, will upda...
Index all *except* one item in python
...you could use a list comp. For example, to make b a copy of a without the 3rd element:
a = range(10)[::-1] # [9, 8, 7, 6, 5, 4, 3, 2, 1, 0]
b = [x for i,x in enumerate(a) if i!=3] # [9, 8, 7, 5, 4, 3, 2, 1, 0]
This is very general, and can be used with all iterables, incl...
Print all but the first three columns
...,$i OFS; if(NF) printf "%s",$NF; printf ORS}'
### Example ###
$ echo '1 2 3 4 5 6 7' |
awk '{for(i=4;i<NF;i++)printf"%s",$i OFS;if(NF)printf"%s",$NF;printf ORS}' |
tr ' ' '-'
4-5-6-7
Sudo_O proposes an elegant improvement using the ternary operator NF?ORS:OFS
$ echo '1 2 3 4 5 6 7' |
aw...
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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Regular Expression to reformat a US phone number in Javascript
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233
Assuming you want the format "(123) 456-7890":
function formatPhoneNumber(phoneNumberString) {...
What does ** (double star/asterisk) and * (star/asterisk) do for parameters?
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2343
The *args and **kwargs is a common idiom to allow arbitrary number of arguments to functions a...
[since C++11] std::array的使用 - C/C++ - 清泛网 - 专注C/C++及内核技术
...类、没有虚函数.
因此不支持这样的构造方法：array<int, 3> a({1, 2, 4});
初始化array最常用的方法是使用赋值运算符和初始化列表：
array<int, 3> a = {1, 2, 3};
array<int, 100> b = {1, 2, 3}; // a[0] ~ a[2] = 1, 2, 3; a[3] ~ a[99] = 0, 0, 0 ... 0;
array<in...