大约有 40,000 项符合查询结果（耗时：0.0431秒） [XML]
How to drop columns by name in a data frame
..."z","u"))]
x y
1 1 2
2 2 3
3 3 4
4 4 5
5 5 6
Or, much simpler, use the select argument of the subset function : you can then use the - operator directly on a vector of column names, and you can even omit the quotes around the names !
R> subset(df, select=-c(z,u))
x y
1 1 2
2 2 3
3 3 4
4 4 ...
Create an Android Jar library for distribution
...ormal Java project in Eclipse, add the android.jar to the build path, then select Export - Java - Jar File.
– Jeff Gilfelt
Feb 16 '11 at 10:47
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How do I check in SQLite whether a table exists?
...sed that FAQ entry.
Anyway, for future reference, the complete query is:
SELECT name FROM sqlite_master WHERE type='table' AND name='{table_name}';
Where {table_name} is the name of the table to check.
Documentation section for reference: Database File Format. 2.6. Storage Of The SQL Database S...
How do I disable text selection with CSS or JavaScript? [duplicate]
...
<div
style="-moz-user-select: none; -webkit-user-select: none; -ms-user-select:none; user-select:none;-o-user-select:none;"
unselectable="on"
onselectstart="return false;"
onmousedown="return false;">
Blabla
</div>
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How to insert text into the textarea at the current cursor position?
...ction insertAtCursor(myField, myValue) {
//IE support
if (document.selection) {
myField.focus();
sel = document.selection.createRange();
sel.text = myValue;
}
//MOZILLA and others
else if (myField.selectionStart || myField.selectionStart == '0') {
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How to flatten nested objects with linq expression
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myBooks.SelectMany(b => b.Chapters
.SelectMany(c => c.Pages
.Select(p => b.Name + ", " + c.Name + ", " + p.Name)));
share
|
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How to achieve code folding effects in Emacs?
...on: C-h k C-x $
tells us that the above key combination is calling
set-selective-display, a function that takes one numerical argument
(the M-1 prefix passes 1 as the value of that argument) and,
unsurprisingly, sets the variable selective-display to the value of
that argument.
from mino...
Select second last element with css
I already know of :last-child. But is there a way to select the div:
2 Answers
2
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SQL Server: Is it possible to insert into two tables at the same time?
...LARE @DataID int;
INSERT INTO DataTable (Column1 ...) VALUES (....);
SELECT @DataID = scope_identity();
INSERT INTO LinkTable VALUES (@ObjectID, @DataID);
COMMIT
The good news is that the above code is also guaranteed to be atomic, and can be sent to the server from a client application w...
How to display the function, procedure, triggers source code in postgresql?
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For function:
you can query the pg_proc view , just as the following
select proname,prosrc from pg_proc where proname= your_function_name;
Another way is that just execute the commont \df and \ef which can list the functions.
skytf=> \df
...