大约有 2,300 项符合查询结果（耗时：0.0426秒） [XML]
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...
Checking if a string can be converted to float in Python
... ------------
print(isfloat("")) False
print(isfloat("1234567")) True
print(isfloat("NaN")) True nan is also float
print(isfloat("NaNananana BATMAN")) False
print(isfloat("123.456")) True
print(isfloat("123.E4")) ...
Lua简明教程 - 更多技术 - 清泛网 - 专注C/C++及内核技术
...行的字符串）
1
2
3
4
5
a = 'alo\n123"'
a = "alo\n123\""
a = '\97lo\10\04923"'
a = [[alo
123"]]
C语言中的NULL在Lua中是nil，比如你访问一个没有声明过的变量，就是nil，比如下面的v的值就是nil
...
Dynamic SQL - EXEC(@SQL) versus EXEC SP_EXECUTESQL(@SQL)
...
EXEC('SELECT * FROM FOO WHERE ID=?', 123) will replace the parameter placeholder "?" with the value 123 and then execute the query, returning a result for SELECT * FROM FOO WHERE ID=123
– Peter Wone
Jun 1 '10 at 23:27
...
sed: print only matching group
...it with a 2nd grep.
# To extract \1 from /xx([0-9]+)yy/
$ echo "aa678bb xx123yy xx4yy aa42 aa9bb" | grep -Eo 'xx[0-9]+yy' | grep -Eo '[0-9]+'
123
4
# To extract \1 from /a([0-9]+)b/
$ echo "aa678bb xx123yy xx4yy aa42 aa9bb" | grep -Eo 'a[0-9]+b' | grep -Eo '[0-9]+'
678
9
...
module.exports vs exports in Node.js
...:
var x = require('file1.js');
contents of file1.js:
module.exports = '123';
When the above statement is executed, a Module object is created. Its constructor function is:
function Module(id, parent) {
this.id = id;
this.exports = {};
this.parent = parent;
if (parent &&...
What's the difference between Task.Start/Wait and Async/Await?
...Thread.Sleep(1000);
WriteOutput("B - Completed something");
return 123;
}
static void WriteOutput(string message)
{
Console.WriteLine("[{0}] {1}", Thread.CurrentThread.ManagedThreadId, message);
}
DoAsTask Output:
[1] Program Begin
[1] 1 - Starting
[1] 2 - Task started
[3] A - Start...
Regex Named Groups in Java
...atching Strings with Balanced Parentheses slide)
Example:
String:
"TEST 123"
RegExp:
"(?<login>\\w+) (?<id>\\d+)"
Access
matcher.group(1) ==> TEST
matcher.group("login") ==> TEST
matcher.name(1) ==> login
Replace
matcher.replaceAll("aaaaa_$1_sssss_$2____") ==> aaa...
CSS \9 in width property
... \0 instead of \9 will apply it to IE10 as well
– abc123
Oct 9 '13 at 21:26
21
@abc123 lets hope ...
How to show full object in Chrome console?
...null,4));
}
// how to call it
let obj = { a: 1, b: [2,3] };
print('hello',123,obj);
will output in console:
[
"hello",
123,
{
"a": 1,
"b": [
2,
3
]
}
]
sha...