大约有 44,000 项符合查询结果（耗时：0.0576秒） [XML]
How to Correctly Use Lists in R?
...dresses the question of the difference between [] and [[]].
In short [[]] selects a single item from a list and [] returns a list of the selected items. In your example, x = list(1, 2, 3, 4)' item 1 is a single integer but x[[1]] returns a single 1 and x[1] returns a list with only one value.
>...
Unique random string generation
...ncat(
Enumerable
.Repeat(0, int.MaxValue)
.Select(e => RandomByte())
.Where(randomByte => randomByte < outOfRange)
.Take(length)
.Select(randomByte => alphabet[randomByte % alphabet.Length])
);
}
byte RandomByte()
{...
Sqlite LIMIT / OFFSET query
...< 100000; i++)
{
//first version
timeLimitOffset += SqlDuraction("Select * from table1 order by col1 LIMIT " + (i + 1) + " OFFSET " + (1001 - i) + "");
// second version
timeLimitComma += SqlDuraction("Select * from table1 order by col1 LIMIT " + (1001 - i) + " , " + (i + 1) + "");
}...
Convert XLS to CSV on command line
...
The code converts only the active worksheet. To select another worksheet, add the following line after the oExcel.Workbooks.Open line with the desired index of the worksheet (starts at 1): oBook.Worksheets(1).Activate
– humbads
Oct 3...
#1071 - Specified key was too long; max key length is 1000 bytes
... the best prefix length for a given column? Here's a method to find out:
SELECT
ROUND(SUM(LENGTH(`menu_link`)<10)*100/COUNT(`menu_link`),2) AS pct_length_10,
ROUND(SUM(LENGTH(`menu_link`)<20)*100/COUNT(`menu_link`),2) AS pct_length_20,
ROUND(SUM(LENGTH(`menu_link`)<50)*100/COUNT(`menu_...
What is Virtual DOM?
...nd what react does it look for the the reference in its object model tree, select the real node in the html and tinker with it. The sound is great virtual dom, but it's nothing fancy and overhype.
– syarul
Feb 15 '17 at 1:07
...
HQL ERROR: Path expected for join
...
select u from UserGroup ug inner join ug.user u
where ug.group_id = :groupId
order by u.lastname
As a named query:
@NamedQuery(
name = "User.findByGroupId",
query =
"SELECT u FROM UserGroup ug " +
"INNER JOIN...
String concatenation does not work in SQLite
...
Try using || in place of +
select locationname || '<p>' from location;
From SQLite documentation:
The || operator is "concatenate" - it joins together the two strings of its operands.
...
Is there a jQuery unfocus method?
...fore the window loses focus so that when I come back, the text area is not selected by default. Doesn't seem to work :(
– Alec Smart
May 13 '09 at 10:55
...
How to set warning level in CMake?
...ractive' strategy for warnings, just like clang's -Weverything. Instead of selecting warnings to enable, you enable everything and then select specific warnings to disable.
– bames53
Sep 7 '16 at 16:59
...