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[6:37:16 PM] I/[YAIL] begin: 2 个子表达式
[6:37:16 PM] I/[YAIL] begin[1]: (require) len=2
[6:37:16 PM] I/[YAIL] begin[2]: (process-repl-input) len=3
[6:37:16 PM] I/[YAIL] begin: 1 个子表达式
[6:37:16 PM] I/[YAIL] begin[1]: (define-event) len=6
[6:37:16 PM] I/[YAIL] ...
Regular expression that matches valid IPv6 addresses
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30 Answers
30
Active
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How do I make a matrix from a list of vectors in R?
...ne option is to use do.call():
> do.call(rbind, a)
[,1] [,2] [,3] [,4] [,5] [,6]
[1,] 1 1 2 3 4 5
[2,] 2 1 2 3 4 5
[3,] 3 1 2 3 4 5
[4,] 4 1 2 3 4 5
[5,] 5 1 2 3 4 5
[6,] 6 1 2 3 ...
C++并发编程（中文版） - 文档下载 - 清泛网 - 专注C/C++及内核技术
...并发… 1
1.1.1 计算机系统的并发… 1
1.1.2 并发的方法… 3
1.2 为什么使用并发… 4
1.2.1 因划分重点而使用并发… 5
1.2.2 为了提高性能而使用并发… 5
1.2.3 什么时候不使用并发… 6
1.3 在C++中使用并发和多线程… 7
1.3.1 多线程...
What is the ultimate postal code and zip regex?
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132
There is none.
Postal/zip codes around the world don't follow a common pattern. In some countr...
Filter rows which contain a certain string
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263
The answer to the question was already posted by the @latemail in the comments above. You can us...
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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Determine the data types of a data frame's columns
...o use ?str(). To explore some examples, let's make some data:
set.seed(3221) # this makes the example exactly reproducible
my.data <- data.frame(y=rnorm(5),
x1=c(1:5),
x2=c(TRUE, TRUE, FALSE, FALSE, FALSE),
X3=letters[1:5])
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Split a vector into chunks in R
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326
A one-liner splitting d into chunks of size 20:
split(d, ceiling(seq_along(d)/20))
More det...
Applying a function to every row of a table using dplyr?
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edited Aug 6 '19 at 3:20
answered Jul 14 '14 at 0:20
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