大约有 40,000 项符合查询结果（耗时：0.0501秒） [XML]
Aggregate / summarize multiple variables per group (e.g. sum, mean)
...-date), sum)
# summarising a specific set of non-grouping variables using select_helpers
# see ?select_helpers for more options
df2 <- df1 %>% group_by(year, month) %>% summarise_at(vars(starts_with('x')), sum)
df2 <- df1 %>% group_by(year, month) %>% summarise_at(vars(matches('.*...
Twitter bootstrap scrollable table
...able;
table-layout: fixed;
}
table{
height:300px; // <-- Select the height of the table
display: -moz-groupbox; // Firefox Bad Effect
}
tbody{
overflow-y: scroll;
height: 200px; // <-- Select the height of the body
width: 100%;
position: absolute;
}...
Problem in running .net framework 4.0 website on iis 7.0
... like (PC-Name)\.
then double click on the ISAPI and CGI Restriction.
then select ASP.NET v4.0.30319(32-bit) Restriction allowed.
share
|
improve this answer
|
follow
...
Which annotation should I use: @IdClass or @EmbeddedId
...and @EmbeddedId is when it comes to write HQL :
With @IdClass you write:
select e.name from Employee e
and with @EmbeddedId you have to write:
select e.employeeId.name from Employee e
You have to write more text for the same query. Some may argue that this differs from a more natural language l...
How to send a command to all panes in tmux?
I like to call :clear-history on panes with a huge scrollback. However, I want to script a way to send this command to all the panes in the various windows.
...
Define css class in django Forms
... The only sane solution, I must say. Thank you!. Python code, and especially in form's definition, is the last place to put stuff for styling - these definitely belong to the templates.
– Boris Chervenkov
Nov 12 '11 at 23:09
...
ViewController respondsToSelector: message sent to deallocated instance (CRASH)
...e where this was performed (If this isn't working, you can examine call by selecting it and choosing its counterpart in Extended Detail pane):
This will let you examine all the retainCount lifecycle of object and probably you'll find your problem right away. All you got to do is find missing reta...
Should import statements always be at the top of a module?
...t that's only paid once.
Putting the imports within a function will cause calls to that function to take longer.
So if you care about efficiency, put the imports at the top. Only move them into a function if your profiling shows that would help (you did profile to see where best to improve perform...
How update the _id of one MongoDB Document?
I want update an _id field of one document. I know it's not a really good pratice. But with some technical reason, I need update it. If I try to update it I get:
...
Creating an abstract class in Objective-C
I'm originally a Java programmer who now works with Objective-C. I'd like to create an abstract class, but that doesn't appear to be possible in Objective-C. Is this possible?
...