大约有 1,708 项符合查询结果（耗时：0.0103秒） [XML]
How to select the row with the maximum value in each group
...
The most intuitive method is to use group_by and top_n function in dplyr
group %>% group_by(Subject) %>% top_n(1, pt)
The result you get is
Source: local data frame [3 x 3]
Groups: Subject [3]
Subject pt Event
(dbl) (dbl) (dbl)
1 ...
How do I set default values for functions parameters in Matlab?
... use "varargs" and check against the number of arguments. Something like:
function f(arg1, arg2, arg3)
if nargin < 3
arg3 = 'some default'
end
end
There are a few fancier things you can do with isempty, etc., and you might want to look at Matlab central for some packages that bundl...
How to break out of nested loops?
...
No, don't spoil the fun with a break. This is the last remaining valid use of goto ;)
If not this then you could use flags to break out of deep nested loops.
Another approach to breaking out of a nested loop is to factor out both loops into ...
App Inventor 2 软件著作权（软著）申请指南 · App Inventor 2 中文网
...经验的，建议找人代理一下，细节还是很多很繁琐的。
fun123.cn 提供专业的 AppInventor 源码软著代申请服务，承诺不下证退全款。
5、注意事项
不要有 Logo——有概率会要求提供证明材料，PS掉就行。
不要有...
Base 64 encode and decode example code
...
For Kotlin mb better to use this:
fun String.decode(): String {
return Base64.decode(this, Base64.DEFAULT).toString(charset("UTF-8"))
}
fun String.encode(): String {
return Base64.encodeToString(this.toByteArray(charset("UTF-8")), Base64.DEFAULT)
}
...
How can I parse a CSV string with JavaScript, which contains comma in data?
...rator may have adjacent whitespace (which is ignored).
Find:
A JavaScript function which converts a valid CSV string (as defined above) into an array of string values.
Solution:
The regular expressions used by this solution are complex. And (IMHO) all non-trivial regular expressions should be prese...
Load dimension value from res/values/dimension.xml from source code
...call context.dp(R.dimen. tutorial_cross_marginTop) to get the Float value
fun Context.px(@DimenRes dimen: Int): Int = resources.getDimension(dimen).toInt()
fun Context.dp(@DimenRes dimen: Int): Float = px(dimen) / resources.displayMetrics.density
If you want to handle it without context, you can...
Count character occurrences in a string in C++
...but I'd suggest you to use this solution instead. As you see you can use a function to encapsulate the code for you so you won't have to write out the for loop everytime, but can just use count_underscores("my_string_") in the rest of your code. Using advanced C++ algorithms is certainly possible he...
data.table vs dplyr: can one do something well the other can't or does poorly?
...ansparency. Updating a data.table object by reference, especially within a function may not be always desirable. But this is an incredibly useful feature: see this and this posts for interesting cases. And we want to keep it.
Therefore we are working towards exporting shallow() function in data.tab...
Shell one liner to prepend to a file
...t just didn't work at all, so it was furiously downvoted for a time. Such fun.
The solution exploits the exact implementation of file descriptors on your system and, because implementation varies significantly between nixes, it's success is entirely system dependent, definitively non-portable, and...