大约有 44,000 项符合查询结果（耗时：0.0400秒） [XML]
What does .SD stand for in data.table in R
...his is your data.table:
DT = data.table(x=rep(c("a","b","c"),each=2), y=c(1,3), v=1:6)
setkey(DT, y)
DT
# x y v
# 1: a 1 1
# 2: b 1 3
# 3: c 1 5
# 4: a 3 2
# 5: b 3 4
# 6: c 3 6
Doing this may help you see what .SD is:
DT[ , .SD[ , paste(x, v, sep="", collapse="_")], by=y]
# y V1
# 1...
Ruby: require vs require_relative - best practice to workaround running in both Ruby =1.
... want to require a relative file in Ruby and I want it to work in both 1.8.x and >=1.9.2?
11 Answers
...
How to sleep for five seconds in a batch file/cmd [duplicate]
...
One hack is to (mis)use the ping command:
ping 127.0.0.1 -n 6 > nul
Explanation:
ping is a system utility that sends ping requests. ping is available on all versions of Windows.
127.0.0.1 is the IP address of localhost. This IP address is guaranteed to always resol...
How do I get Month and Date of JavaScript in 2 digit format?
...tDate()).slice(-2)
for the date, and similar:
("0" + (this.getMonth() + 1)).slice(-2)
for the month.
share
|
improve this answer
|
follow
|
...
Truncating floats in Python
...
117
First, the function, for those who just want some copy-and-paste code:
def truncate(f, n):
...
When is memoization automatic in GHC Haskell?
I can't figure out why m1 is apparently memoized while m2 is not in the following:
4 Answers
...
What belongs in an educational tool to demonstrate the unwarranted assumptions people make in C/C++?
...
91
The order of evaluation of subexpressions, including
the arguments of a function call and
oper...
Easy way to test a URL for 404 in PHP?
...
15 Answers
15
Active
...
SQL Server dynamic PIVOT query?
...me,
category varchar(3),
amount money
)
insert into temp values ('1/1/2012', 'ABC', 1000.00)
insert into temp values ('2/1/2012', 'DEF', 500.00)
insert into temp values ('2/1/2012', 'GHI', 800.00)
insert into temp values ('2/10/2012', 'DEF', 700.00)
insert into temp values ('3/1/2012', 'ABC...
How can I show ellipses on my TextView if it is greater than the 1 line?
...droid:scrollHorizontally="true"
android:ellipsize="end"
android:maxLines="1"
.............. the scrollHorizontally is the "special sauce" that makes it work.
share
|
improve this answer
...