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Which is faster in Python: x**.5 or math.sqrt(x)?
... (Python 2.5.2, Windows):
$ python -mtimeit -s"from math import sqrt; x = 123" "x**.5"
1000000 loops, best of 3: 0.445 usec per loop
$ python -mtimeit -s"from math import sqrt; x = 123" "sqrt(x)"
1000000 loops, best of 3: 0.574 usec per loop
$ python -mtimeit -s"import math; x = 123" "math.sqrt(x...
How to represent multiple conditions in a shell if statement?
...
Classic technique (escape metacharacters):
if [ \( "$g" -eq 1 -a "$c" = "123" \) -o \( "$g" -eq 2 -a "$c" = "456" \) ]
then echo abc
else echo efg
fi
I've enclosed the references to $g in double quotes; that's good practice, in general. Strictly, the parentheses aren't needed because the preced...
php中json_decode()和json_encode()的使用方法 - 更多技术 - 清泛网 - 专注C/C++及内核技术
...d"] => int(4)
["e"] => int(5)
}
$data='[
{"Name":"a1","Number":"123","Contno":"000","QQNo":""},
{"Name":"a1","Number":"123","Contno":"000","QQNo":""},
{"Name":"a1","Number":"123","Contno":"000","QQNo":""}
]';
echo json_decode($data);
结果为：
Array ( [0] => stdClass Object ( ...
How do I split a string, breaking at a particular character?
...h JavaScript’s String.prototype.split function:
var input = 'john smith~123 Street~Apt 4~New York~NY~12345';
var fields = input.split('~');
var name = fields[0];
var street = fields[1];
// etc.
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Can functions be passed as parameters?
...ing.
func value(x int) string {
return fmt.Sprintf("%v", x)
}
// quote123 passes 123 to convert func and returns quoted string.
func quote123(fn convert) string {
return fmt.Sprintf("%q", fn(123))
}
func main() {
var result string
result = value(123)
fmt.Println(result)
//...
How to display pandas DataFrame of floats using a format string for columns?
... pd
pd.options.display.float_format = '${:,.2f}'.format
df = pd.DataFrame([123.4567, 234.5678, 345.6789, 456.7890],
index=['foo','bar','baz','quux'],
columns=['cost'])
print(df)
yields
cost
foo $123.46
bar $234.57
baz $345.68
quux $456.79
but this ...
Linq code to select one item
...e extension methods directly like:
var item = Items.First(i => i.Id == 123);
And if you don't want to throw an error if the list is empty, use FirstOrDefault which returns the default value for the element type (null for reference types):
var item = Items.FirstOrDefault(i => i.Id == 123);
...
Detect if value is number in MySQL
...l1 * 1) = col1
It doesn't work for non-standard numbers like
1e4
1.2e5
123. (trailing decimal)
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App Inventor 2 扩展 · App Inventor 2 中文网
... Camera or LocationSensor) or services on the Web (like Twitter or FusionTables). App Inventor includes a large collection of components, and the App Inventor development team adds new capabilities to the system by implementing new components.
There have been many requests to include additional f...