大约有 43,000 项符合查询结果（耗时：0.0273秒） [XML]
Pass a data.frame column name to a function
...1(df, "B")
fun1(df, c("B","A"))
There's no need to use substitute, eval, etc.
You can even pass the desired function as a parameter:
fun1 <- function(x, column, fn) {
fn(x[,column])
}
fun1(df, "B", max)
Alternatively, using [[ also works for selecting a single column at a time:
df <- ...
What Ruby IDE do you prefer? [closed]
...xclusively for PHP/Ruby development, and standard Eclipse for JAVA, C, C++ etc. This prevents me from dealing with pointless warnings.
– Zee Spencer
Jun 18 '10 at 14:40
2
...
How to create a readonly textbox in ASP.NET MVC3 Razor
...nly see it with keywords that match HTML attributes (like readonly, class, etc.)
– Brad Christie
Jan 6 '12 at 17:40
10
...
Closing Database Connections in Java
...method in order to release any other database resources (cursors, handles, etc) the connection may be holding on to.
Actually, the safe pattern in Java is to close your ResultSet, Statement, and Connection (in that order) in a finally block when you are done with them, something like that:
Connec...
How to download source in ZIP format from GitHub?
...ut downloading the whole thing each time and writing over your own changes etc. A ZIP file won't let you do that.
It is mostly meant for people who want to develop the source rather than people who just want to get the source one off and not make changes.
But it just so happens you can get a ZIP f...
Is XSLT worth it? [closed]
...ow you to debug directly within XSL files. Setting breakpoints, inspecting etc.
– Craig Bovis
May 20 '09 at 14:10
This...
git: fatal: Could not read from remote repository
... Thanks a Lot.. This finally worked for me after trying to create, delete, etc the SSH keys into my GitLab account.... Thanks!!
– Bms bharadwaj
Jul 22 '19 at 13:13
...
What are named pipes?
...ome metadata (You can obtain the credentials of the thing on the other end etc).
Unix named pipes appear as a special file in the filesystem and can be accessed with normal file IO commands including the shell. Windows ones don't, and need to be opened with a special system call (after which they b...
C++ IDE for Linux? [closed]
...t with the various tools — Debuggers (gdb), Profilers (gprof, valgrind), etc. You set up your project/build environment using Make, CMake, SnakeMake or any of the various alternatives. And you manage your code with a version control system (most people use Git). You also use tmux (previously also ...
How do I show/hide a UIBarButtonItem?
...TextAttributes :- This works great on bar button items like "Done", "Save" etc. However, it does not work on items like Add, Trash symbol etc.(atleast not for me) since they are not texts.
use TintColor :- If I have a bar button item called "deleteButton" :-
To hide the button, I used the followin...