大约有 48,000 项符合查询结果（耗时：0.0342秒） [XML]
Is there a good charting library for iPhone? [closed]
...rs working on this, so I'd expect it to advance rapidly. Also, the Google Group for this is at groups.google.com/group/coreplot-discuss?hl=en . The archives are worth reading through, to see where people are going with this.
– Brad Larson♦
Apr 20 '09 at 22:5...
What is the difference between return and return()?
... is a language statement. All you're doing with the parentheses is simply grouping your return value so it can be evaluated. For instance, you could write:
return (x == 0);
In this case, you return the value of the statement x == 0, which will return a boolean true or false depending on the val...
How do I get SUM function in MySQL to return '0' if no values are found?
...
Isn't SELECT SUM(IFNULL(column,0)) FROM table GROUP BY something more correct? What if we have some IS NULL values and some real values in "column"?
– DarkSide
Nov 11 '13 at 15:03
...
Why does Iterable not provide stream() and parallelStream() methods?
...on the EG list in June of 2013.
The definitive discussion of the Expert Group is rooted at this thread.
While it seemed "obvious" (even to the Expert Group, initially) that stream() seemed to make sense on Iterable, the fact that Iterable was so general became a problem, because the obvious sign...
How to extract the first two characters of a string in shell scripting?
...nction to extract the first two characters and the fourth uses sed capture groups (using () and \1) to capture the first two characters and replace the entire line with them. They're both similar to cut - they deliver the first two characters of each line in the input.
None of that matters if you a...
How to get the part of a file after the first line that matches a regular expression?
...railing context after matching lines.
Places a line containing a group separator (--) between
contiguous groups of matches. With the -o or --only-matching
option, this has no effect and a warning is given.
...
What's the fastest way to merge/join data.frames in R?
...e index ix on d(g1, g2)",
"select g1, g2, avg(x), avg(y) from main.d group by g1, g2"))
)
The outputs from the two benchmark call comparing the merge calculations are:
Joining by: x
test replications elapsed relative user.self sys.self user.child sys.child
3 data.table 1 ...
Convert list to dictionary using linq and not worrying about duplicates
...
LINQ solution:
// Use the first value in group
var _people = personList
.GroupBy(p => p.FirstandLastName, StringComparer.OrdinalIgnoreCase)
.ToDictionary(g => g.Key, g => g.First(), StringComparer.OrdinalIgnoreCase);
// Use the last value in group
...
What is the error “Every derived table must have its own alias” in MySQL?
...Here's a different example that can't be rewritten without aliases ( can't GROUP BY DISTINCT).
Imagine a table called purchases that records purchases made by customers at stores, i.e. it's a many to many table and the software needs to know which customers have made purchases at more than one stor...
Difference between framework vs Library vs IDE vs API vs SDK vs Toolkits? [closed]
...terface to the library.
An SDK (software development kit) is a library or group of libraries (often with extra tool applications, data files and sample code) that aid you in developing code that uses a particular system (e.g. extension code for using features of an operating system (Windows SDK), d...