大约有 40,000 项符合查询结果（耗时：0.0403秒） [XML]
Split data frame string column into multiple columns
...
Use stringr::str_split_fixed
library(stringr)
str_split_fixed(before$type, "_and_", 2)
share
|
improve this answer
|
...
Insert auto increment primary key to existing table
...ering if it's possible to insert data into the primary key column automatically (I already have 500 rows in DB and want to give them id but I don't want to do it manually). Any thoughts? Thanks a lot.
...
Dynamic instantiation from string name of a class in dynamically imported module?
...
You can use getattr
getattr(module, class_name)
to access the class. More complete code:
module = __import__(module_name)
class_ = getattr(module, class_name)
instance = class_()
As mentioned below, we may use importlib
import importlib
module = importlib.imp...
Why isn't `int pow(int base, int exponent)` in the standard C++ libraries?
... of power functions (and others). C++11 [c.math] /11 states, after listing all the float/double/long double overloads (my emphasis, and paraphrased):
Moreover, there shall be additional overloads sufficient to ensure that, if any argument corresponding to a double parameter has type double or an...
How do I use a custom deleter with a std::unique_ptr member?
...is solution is that it doubles the overhead of every unique_ptr (they must all store the function pointer along with the pointer to the actual data), requires passing the destruction function every time, it can't inline (since the template can't specialize to the specific function, only the signatur...
How to get a reference to current module's attributes in Python
...he way I typically see this done is like this:
import sys
dir(sys.modules[__name__])
share
|
improve this answer
|
follow
|
...
Restoring MySQL database from physical files
...mysql data directory is quick and easy, but figuring out, before that, why all my resoterd DBs seemed to have no tables took a bit longer.
– Edurne Pascual
Sep 26 '12 at 15:41
10
...
Cross field validation with Hibernate Validator (JSR 303)
... fields; cross-field validation should be done at the class level. Additionally, the JSR-303 Section 2.2 preferred way to express multiple validations of the same type is via a list of annotations. This allows the error message to be specified per match.
For example, validating a common form:
@F...
ASP.NET MVC Razor pass model to layout
...have modeled your viewmodels a bit wrong if you have this problem.
Personally I would never type a layout page. But if you want to do that you should have a base viewmodel that your other viewmodels inherits from and type your layout to the base viewmodel and you pages to the specific once.
...
How to get RelativeLayout working with merge and include?
...
This is really easier, less hardcoded, and more optimized solution than packing <include/> into another layout. Think what would you do if you would work with lists.
– teoREtik
Feb 2 '12 at ...