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...37:16 PM] I/→ SimpleYail 执行
[6:37:16 PM] I/[YAIL] 解析 YAIL (541 chars)
[6:37:16 PM] I/[YAIL] 解析得到 1 个顶层表达式
[6:37:16 PM] I/[YAIL] 执行[0]: (begin ...) len=3
[6:37:16 PM] I/[YAIL] begin: 2 个子表达式
[6:37:16 PM] I/[YAIL] begin[1]: (require) len=2...
Regular expression that matches valid IPv6 addresses
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254
I was unable to get @Factor Mystic's answer to work with POSIX regular expressions, so I wrote o...
How do I make a matrix from a list of vectors in R?
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124
One option is to use do.call():
> do.call(rbind, a)
[,1] [,2] [,3] [,4] [,5] [,6]
[...
C++并发编程（中文版） - 文档下载 - 清泛网 - 专注C/C++及内核技术
...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 多线程在C++中的发展历程… 7
1.3.2...
What is the ultimate postal code and zip regex?
...le IMO. But you would still be missing on the validation part: Zip code 12345 may exist, but 12346 not, maybe 12344 doesn't exist either. How do you check for that with a regex?
You can't.
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Filter rows which contain a certain string
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4 Answers
4
Active
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Assign multiple columns using := in data.table, by group
...b col1 col2
# 1: 1 1 hi hello
# 2: 2 2 hi hello
# 3: 3 3 hi hello
# 4: 1 4 hi hello
# 5: 2 5 hi hello
# 6: 3 6 hi hello
x[ , c("mean", "sum") := list(mean(b), sum(b)), by = a][]
# a b col1 col2 mean sum
# 1: 1 1 hi hello 2.5 5
# 2: 2 2 hi hello 3.5 7
# 3: 3 3 hi hello ...
Determine the data types of a data frame's columns
...st few values of each variable):
str(my.data)
'data.frame': 5 obs. of 4 variables:
$ y : num 1.03 1.599 -0.818 0.872 -2.682
$ x1: int 1 2 3 4 5
$ x2: logi TRUE TRUE FALSE FALSE FALSE
$ X3: Factor w/ 5 levels "a","b","c","d",..: 1 2 3 4 5
@Gavin Simpson's approach is also streamlined, but p...
Split a vector into chunks in R
...(), split() and ceiling():
> d <- rpois(73,5)
> d
[1] 3 1 11 4 1 2 3 2 4 10 10 2 7 4 6 6 2 1 1 2 3 8 3 10 7 4
[27] 3 4 4 1 1 7 2 4 6 0 5 7 4 6 8 4 7 12 4 6 8 4 2 7 6 5
[53] 4 5 4 5 5 8 7 7 7 6 2 4 3 3 8 11 6 6 1 8 4
> m...
Applying a function to every row of a table using dplyr?
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answered Jul 14 '14 at 0:20
alexwhanalexwhan
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