大约有 4,000 项符合查询结果（耗时：0.0114秒） [XML]
Generic TryParse
... it's simply a matter of calling thusly:
var value = TryParse<int>("123", int.TryParse);
var value2 = TryParse<decimal>("123.123", decimal.TryParse);
share
|
improve this answer
...
Does bit-shift depend on endianness?
...rticles: codeproject.com/KB/cpp/endianness.aspx and ibm.com/developerworks/aix/library/au-endianc/…
– Carl
Sep 4 '11 at 23:39
3
...
Can you supply arguments to the map(&:method) syntax in Ruby?
...
I like this solution, but I think you can have even more fun with it. Instead of defining a with method, define call. Then you can do things like a.map(&:+.(2)) since object.() uses the #call method. And while you're at it, you can write fun things like :+.(2).(3) #=> 5 -...
C# short/long/int literal format?
...by F or f is of type float. For example, the literals 1f, 1.5f, 1e10f, and 123.456F are all of type float.
A real literal suffixed by D or d is of type double. For example, the literals 1d, 1.5d, 1e10d, and 123.456D are all of type double.
A real literal suffixed by M or m is of type decimal. For ex...
SQL query for finding records where count > 1
...p int(11) not null,
dt date not null
);
insert into payment values
(1,123,55555,'2009-12-12'),
(1,123,66666,'2009-12-12'),
(1,123,77777,'2009-12-13'),
(2,456,77777,'2009-12-14'),
(2,456,77777,'2009-12-14'),
(2,789,77777,'2009-12-14'),
(2,789,77777,'2009-12-14');
select foo.user_id, foo.cnt fro...
Can the jQuery UI Datepicker be made to disable Saturdays and Sundays (and holidays)?
...r'], [6, 6, 'se'],
[7, 4, 'us'], [8, 17, 'id'], [9, 7, 'br'],
[10, 1, 'cn'], [11, 22, 'lb'], [12, 12, 'ke']
];
function nationalDays(date) {
for (i = 0; i < natDays.length; i++) {
if (date.getMonth() == natDays[i][0] - 1
&& date.getDate() == natDays[i][1]) {
...
Does Java read integers in little endian or big endian?
...mats that use some form of Huffman encoding (i.e. all of them). For extra fun, JPEG is "bitwise big-endian" (i.e. the most significant bit is the "first" bit) and LZ is "bitwise little-endian". I once worked on a proprietary compression format that used both formats under the hood. Oh, that was f...
sphinx-build fail - autodoc can't import/find module
... traceback it seems clear that the modules are not in sys.path, so autodoc cn't find them. The .rst files are found.
– bmu
Jun 17 '12 at 7:55
add a comment
...
Is there a way to get a collection of all the Models in your Rails app?
...ase. Don't know how you can list all the classes though...
EDIT: Just for fun, I found a way to list all classes
Module.constants.select { |c| (eval c).is_a? Class }
EDIT: Finally succeeded in listing all models without looking at directories
Module.constants.select do |constant_name|
constan...
Remove duplicated rows using dplyr
...ction for this purpose.
Original answer below:
library(dplyr)
set.seed(123)
df <- data.frame(
x = sample(0:1, 10, replace = T),
y = sample(0:1, 10, replace = T),
z = 1:10
)
One approach would be to group, and then only keep the first row:
df %>% group_by(x, y) %>% filter(row_nu...