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Changing column names of a data frame
...
Use the colnames() function:
R> X <- data.frame(bad=1:3, worse=rnorm(3))
R> X
bad worse
1 1 -2.440467
2 2 1.320113
3 3 -0.306639
R> colnames(X) <- c("good", "better")
R> X
good better
1 1 -2.440467
2 2 1.320113
3 3...
How do I check if an object has a specific property in JavaScript?
...imply reducing the property check to typeof this[property] or, even worse, x.key will give you completely misleading results.
It depends on what you're looking for. If you want to know if an object physically contains a property (and it is not coming from somewhere up on the prototype chain) then o...
What is the difference between old style and new style classes in Python?
...The concept of (old-style) class is unrelated to the concept of type:
if x is an instance of an old-style class, then x.__class__
designates the class of x, but type(x) is always <type
'instance'>.
This reflects the fact that all old-style instances, independently of
their class,...
What's the difference between `=` and `
...as the operator = is only allowed at the top level (e.g., in the complete expression typed at the command prompt) or as one of the subexpressions in a braced list of expressions.
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Pairwise crossproduct in Python [duplicate]
...,5,6]
>>> itertools.product(a,b)
<itertools.product object at 0x10049b870>
>>> list(itertools.product(a,b))
[(1, 4), (1, 5), (1, 6), (2, 4), (2, 5), (2, 6), (3, 4), (3, 5), (3, 6)]
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Error in if/while (condition) {: missing Value where TRUE/FALSE needed
...where TRUE/FALSE needed
To test whether an object is missing use is.na(x) rather than x == NA.
See also the related errors:
Error in if/while (condition) { : argument is of length zero
Error in if/while (condition) : argument is not interpretable as logical
if (NULL) {}
## Error in if (NUL...
据说这是一个程序员的手机......... - 轻松一刻 - 清泛网 - 专注C/C++及内核技术
据说这是一个程序员的手机.........程序猿的读书历程：x语言入门—>x语言应用实践—>x语言高阶编程—>x语言的科学与艺术—>编程之美—>编程之道—>编程之禅—>颈椎病康复指南...程序猿的读书历程：x语言入门—>x语言应用实践...
oracle10g 网址收藏 - 数据库(内核) - 清泛网 - 专注C/C++及内核技术
... Release 2 (10.2.0.1.0) Enterprise/Standard Edition for Microsoft Windows (x64)
http://download.oracle.com/otn/nt/oracle10g/10201/102010_win64_x64_database.zip
http://download.oracle.com/otn/nt/oracle10g/10201/102010_win64_x64_client.zip
http://download.oracle.com/otn/nt/oracle10g/10201/1020...
推荐引擎easyrec半天学习分享 - 大数据 & AI - 清泛网 - 专注C/C++及内核技术
...='http://localhost:8080/easyrec-web/js/jquery/jquery-1.4.2.min.js' type='text/javascript'></script>
<script src='http://localhost:8080/easyrec-web/js/easyrec.js' type='text/javascript'></script>
c.编写一段调用代码：
$(function(){
$.getJSON(
"/easyrec-web/api/1.0/json/otherusersal...
覆盖equal时的通用约定 - 更多技术 - 清泛网 - 专注C/C++及内核技术
...通用约定自反性、对称性、传递性、一致性1、自反性：x.equal(x) = true;
2、对称性：x.equal(y) = y.equal(x);
3、传递性：x.equal(y) = y.equal(z) = x.equal(z);
4、一致性：x.equal(y) 不改变值的情况下多次调用结果一致。
（假定x, y, z非null）
...