大约有 43,000 项符合查询结果（耗时：0.0258秒） [XML]
What is the Ruby (spaceship) operator?
...roovy is another language that supports it. Basically instead of returning 1 (true) or 0 (false) depending on whether the arguments are equal or unequal, the spaceship operator will return 1, 0, or −1 depending on the value of the left argument relative to the right argument.
a <=> b :=
i...
Apply a function to every row of a matrix or a data frame
...
182
You simply use the apply() function:
R> M <- matrix(1:6, nrow=3, byrow=TRUE)
R> M
...
Replace all 0 values to NA
...
Replacing all zeroes to NA:
df[df == 0] <- NA
Explanation
1. It is not NULL what you should want to replace zeroes with. As it says in ?'NULL',
NULL represents the null object in R
which is unique and, I guess, can be seen as the most uninformative and empty object.1 Then it b...
浅析为什么char类型的范围是 -128~+127 - C/C++ - 清泛网 - 专注C/C++及内核技术
浅析为什么char类型的范围是 -128~+127在C语言中， signed char 类型的范围为-128~127,每本教科书上也这么写，但是没有哪一本书上（包括老师）也不会给你为什么是-128~127，这...在C语言中， signed char 类型的范围为-128~127,每本教科书上...
Calculate difference in keys contained in two Python dictionaries
...
21 Answers
21
Active
...
Type-juggling and (strict) greater/lesser-than comparisons in PHP
...
|
edited May 23 '17 at 11:47
Community♦
111 silver badge
answered Apr 4 '13 at 14:10
...
Pandas index column title or name
...'
In [8]: df.index.name = 'foo'
In [9]: df.index.name
Out[9]: 'foo'
In [10]: df
Out[10]:
Column 1
foo
Apples 1
Oranges 2
Puppies 3
Ducks 4
share
|
...
Regex to validate date format dd/mm/yyyy
...post.
I modified it to take dd/mm/yyyy, dd-mm-yyyy or dd.mm.yyyy.
^(?:(?:31(\/|-|\.)(?:0?[13578]|1[02]))\1|(?:(?:29|30)(\/|-|\.)(?:0?[13-9]|1[0-2])\2))(?:(?:1[6-9]|[2-9]\d)?\d{2})$|^(?:29(\/|-|\.)0?2\3(?:(?:(?:1[6-9]|[2-9]\d)?(?:0[48]|[2468][048]|[13579][26])|(?:(?:16|[2468][048]|[3579][26])00))))$...