大约有 47,000 项符合查询结果（耗时：0.0495秒） [XML]
Sort rows in data.table in decreasing order on string key `order(-x,v)` gives error on data.table 1.
...r necessary.
You can use DT[order(-rank(x), y)].
x y v
1: c 1 7
2: c 3 8
3: c 6 9
4: b 1 1
5: b 3 2
6: b 6 3
7: a 1 4
8: a 3 5
9: a 6 6
share
|
improve this answer
|
fol...
How to slice an array in Bash
... |
edited Jul 24 '18 at 16:35
Nicholas Pipitone
3,33511 gold badge1717 silver badges3333 bronze badges
...
How to count the number of set bits in a 32-bit integer?
8 bits representing the number 7 look like this:
55 Answers
55
...
Keep only first n characters in a string?
...JavaScript's String method substring
e.g.
'Hiya how are you'.substring(0,8);
Which returns the string starting at the first character and finishing before the 9th character - i.e. 'Hiya how'.
substring documentation
sha...
How do I use arrays in C++?
...t are easier to use and less error-prone ( std::vector<T> since C++98 and std::array<T, n> since C++11 ), so the need for arrays does not arise quite as often as it does in C. However, when you read legacy code or interact with a library written in C, you should have a firm grasp on ...
How to check the version before installing a package using apt-get?
... |
edited Jul 6 at 8:51
jotadepicas
1,99922 gold badges1919 silver badges4242 bronze badges
answe...
Reset keys of array elements in php?
...
|
edited Jun 7 '18 at 19:04
Riz-waan
54322 silver badges1212 bronze badges
answered May 8 '12 a...
Enable Vim Syntax Highlighting By Default
...
answered Jun 30 '12 at 8:00
Ilmo EuroIlmo Euro
4,45511 gold badge2424 silver badges2727 bronze badges
...
Iterating Through a Dictionary in Swift
...rs = [
"Prime": [2, 3, 5, 7, 11, 13],
"Fibonacci": [1, 1, 2, 3, 5, 8],
"Square": [1, 4, 9, 16, 25]
]
var largest = 0
for (kind, numbers) in interestingNumbers {
println("kind: \(kind)")
for number in numbers {
if number > largest {
largest = number
...
Change MySQL default character set to UTF-8 in my.cnf?
...e are using the following commands in PHP to set the character set to UTF-8 in our application.
18 Answers
...