大约有 35,455 项符合查询结果（耗时：0.0339秒） [XML]
php is null or empty?
...LL) {...}
Note the ===.
When use ==, as you did, PHP treats NULL, false, 0, the empty string, and empty arrays as equal.
share
|
improve this answer
|
follow
...
What is a regular expression for a MAC Address?
...
The standard (IEEE 802) format for
printing MAC-48 addresses in
human-friendly form is six groups of
two hexadecimal digits, separated by
hyphens - or colons :.
So:
^([0-9A-Fa-f]{2}[:-]){5}([0-9A-Fa-f]{2})$
...
WPF ToolBar: how to remove grip and overflow
...
answered Jun 26 '09 at 20:57
rmoorermoore
14.2k44 gold badges5656 silver badges5959 bronze badges
...
Pandas dataframe get first row of each group
...column:
>>> df.groupby('id').first().reset_index()
id value
0 1 first
1 2 first
2 3 first
3 4 second
4 5 first
5 6 first
6 7 fourth
To get n first records, you can use head():
>>> df.groupby('id').head(2).reset_index(drop=True)
id value
0 ...
How to fix the uninitialized constant Rake::DSL problem on Heroku?
...
205
Put this in your Rakefile above require 'rake':
require 'rake/dsl_definition'
...
How can I autoplay a video using the new embed code style for Youtube?
...
+50
Just put "?autoplay=1" in the url the video will autoload.
So your url would be:
http://www.youtube.com/embed/JW5meKfy3fY?autoplay=1
...
how to rotate a bitmap 90 degrees
There is a statement in android canvas.drawBitmap(visiblePage, 0, 0, paint);
10 Answers
...
Principal component analysis in Python
...
|
edited Sep 3 '10 at 11:40
nikow
19.6k66 gold badges4242 silver badges6969 bronze badges
answe...
Is there an equivalent to e.PageX position for 'touchstart' event as there is for click event?
...
180
Kinda late, but you need to access the original event, not the jQuery massaged one. Also, since...
Can dplyr package be used for conditional mutating?
...
220
Use ifelse
df %>%
mutate(g = ifelse(a == 2 | a == 5 | a == 7 | (a == 1 & b == 4), 2,
...