大约有 41,000 项符合查询结果（耗时：0.0500秒） [XML]
Selecting only numeric columns from a data frame
...list-apply functions:
nums <- unlist(lapply(x, is.numeric))
Then standard subsetting
x[ , nums]
## don't use sapply, even though it's less code
## nums <- sapply(x, is.numeric)
For a more idiomatic modern R I'd now recommend
x[ , purrr::map_lgl(x, is.numeric)]
Less codey, less ref...
Add new field to every document in a MongoDB collection
...to add a new_field to all your collection, you have to use empty selector, and set multi flag to true (last param) to update all the documents
db.your_collection.update(
{},
{ $set: {"new_field": 1} },
false,
true
)
EDIT:
In the above example last 2 fields false, true specifies the upser...
Angularjs - display current date
I got a view in angularjs and I'm just trying to display the current date(formatted). I thought something like <span>{{Date.now() | date:'yyyy-MM-dd'}}</span> should display the current date.
...
What's the UIScrollView contentInset property for?
...e what the contentInset property in a UIScrollView instance is used for? And maybe provide an example?
5 Answers
...
Disabling highlighting of current line in the Visual Studio editor
...mple way to disable this highlighting? Otherwise, which parameter in Fonts and Colors dialog controls the background color of the currently selected line in the editor?
...
Can I set an opacity only to the background image of a div?
...nnot be done since opacity affects the whole element including its content and there's no way to alter this behavior. You can work around this with the two following methods.
Secondary div
Add another div element to the container to hold the background. This is the most cross-browser friendly meth...
How to force an entire layout View refresh?
...nflate(int, ViewGroup)).
The API doc reference is here: http://developer.android.com/reference/android/view/ContextThemeWrapper.html#setTheme%28int%29
Since the onDraw() method works on already instantiated Views, setTheme will not work. I have no experience with themes myself, but two alternativ...
How do I set the rounded corner radius of a color drawable using xml?
On the android website, there is a section about color drawables . Defining these drawables in xml looks like this:
3 Ans...
Find object in list that has attribute equal to some value (that meets any condition)
... None)
This gets the first item from the list that matches the condition, and returns None if no item matches. It's my preferred single-expression form.
However,
for x in test_list:
if x.value == value:
print("i found it!")
break
The naive loop-break version, is perfectly Pytho...
JSLint: was used before it was defined
...a separated list of names. Each name can optionally be followed by a colon and either true or false, true indicating that the variable may be assigned to by this file, and false indicating that assignment is not allowed (which is the default). The directive respects function scope.
Some globals...