大约有 46,000 项符合查询结果（耗时：0.0519秒） [XML]
All falsey values in JavaScript
...
Falsey values in JavaScript
false
Zero of Number type: 0 and also -0, 0.0, and hex form 0x0 (thanks RBT)
Zero of BigInt type: 0n and -0n (new in 2020, thanks GetMeARemoteJob)
"", '' and `` - strings of length 0
null
undefined
NaN
document.all (in HTML browsers only)
This is a ...
What's the fastest way to loop through an array in JavaScript?
...yntactically obvious).
A standard for-loop with length caching
var i = 0, len = myArray.length;
while (i < len) {
// your code
i++
}
I would say, this is definitely a case where I applaud JavaScript engine developers. A runtime should be optimized for clarity, not cle...
Apply a function to every row of a matrix or a data frame
... 3 4
[3,] 5 6
R> apply(M, 1, function(x) 2*x[1]+x[2])
[1] 4 10 16
R>
This takes a matrix and applies a (silly) function to each row. You pass extra arguments to the function as fourth, fifth, ... arguments to apply().
...
How to debug Lock wait timeout exceeded on MySQL?
...***
Type: InnoDB
Name:
Status:
=====================================
110514 19:44:14 INNODB MONITOR OUTPUT
=====================================
Per second averages calculated from the last 4 seconds
----------
SEMAPHORES
----------
OS WAIT ARRAY INFO: reservation count 9014315, signal count 780...
How to extract the decision rules from scikit-learn decision-tree?
... print "{}return {}".format(indent, tree_.value[node])
recurse(0, 1)
This prints out a valid Python function. Here's an example output for a tree that is trying to return its input, a number between 0 and 10.
def tree(f0):
if f0 <= 6.0:
if f0 <= 1.5:
return [[ 0.]]
...
How to get line count of a large file cheaply in Python?
...
40 Answers
40
Active
...
Reset C int array to zero : the fastest way?
Assuming that we have a T myarray[100] with T = int, unsigned int, long long int or unsigned long long int, what is the fastest way to reset all its content to zero (not only for initialization but to reset the content several times in my program)? Maybe with memset?
...
JS Client-Side Exif Orientation: Rotate and Mirror JPEG Images
...erver or anything.
– igneosaur
May 20 '16 at 8:28
3
@igneosaur: you can send base64 encoded data ...
How do I replace NA values with zeros in an R dataframe?
...nt in @gsk3 answer. A simple example:
> m <- matrix(sample(c(NA, 1:10), 100, replace = TRUE), 10)
> d <- as.data.frame(m)
V1 V2 V3 V4 V5 V6 V7 V8 V9 V10
1 4 3 NA 3 7 6 6 10 6 5
2 9 8 9 5 10 NA 2 1 7 2
3 1 1 6 3 6 NA 1 4 1 6
4 NA 4 NA 7 10 2 NA 4 1...
Is it possible to change only the alpha of a rgba background colour on hover?
... { display: block; position: relative; }
div { position: absolute; bottom: 0; background-color: rgba(var(--rgb), 0.8); }
a:hover div { background-color: rgba(var(--rgb), 1); }
To understand how this works, see How do I apply opacity to a CSS color variable?
If custom properties are not an option,...