大约有 40,000 项符合查询结果（耗时：0.0664秒） [XML]
How to succinctly write a formula with many variables from a data frame?
...
There is a special identifier that one can use in a formula to mean all the variables, it is the . identifier.
y <- c(1,4,6)
d <- data.frame(y = y, x1 = c(4,-1,3), x2 = c(3,9,8), x3 = c(4,-4,-2))
mod <- lm(y ~ ., data = d)
You can also do things like this, to use all variables but...
How do I check that a Java String is not all whitespaces?
...ity of the question :) Also, I rarely use matches(): for performance, I usually store the Pattern in a final static. Pays off if the same code runs frequently.
– Carl Smotricz
Jul 14 '10 at 14:31
...
How to permanently disable region-folding in Visual Studio 2008
... folding in visual studio 2008? Some of my colleagues love it, but I personally always want to see all the code, and never want code folded out of sight. I'd like a setting that means my copy of Visual Studio never folds #regions or function bodies.
...
Fetch frame count with ffmpeg
...default=nokey=1:noprint_wrappers=1 input.mp4
This is a fast method.
Not all formats (such as Matroska) will report the number of frames resulting in the output of N/A. See the other methods listed below.
ffprobe: Count the number of frames
ffprobe -v error -count_frames -select_streams v:0 -sh...
Linux command: How to 'find' only text files?
...of find such as on OS X, but it doesn't hurt anything just having it there all the time if you want to put this in an alias or something.
EDIT: As @ruslan correctly pointed out, the -and can be omitted since it is implied.
...
How to select option in drop down using Capybara
...t method, you can see that what it does when you pass a from key is essentially:
find(:select, from, options).find(:option, value, options).select_option
In other words, it finds the <select> you're interested in, then finds the <option> within that, then calls select_option on the &l...
How to get all options of a select using jQuery?
How can I get all the options of a select through jQuery by passing on its ID?
17 Answers
...
Set scroll position
...'m trying to set the scroll position on a page so the scroller is scrolled all the way to the top.
4 Answers
...
Calculating moving average
...y helpful though. There doesn't seem to be a built-in function in R will allow me to calculate moving averages. Do any packages provide one? Or do I need to write my own?
...
What is meant by “managed” vs “unmanaged” resources in .NET?
...
The term "unmanaged resource" is usually used to describe something not directly under the control of the garbage collector. For example, if you open a connection to a database server this will use resources on the server (for maintaining the connection) and po...