大约有 44,000 项符合查询结果（耗时：0.0576秒） [XML]
Getting current date and time in JavaScript
I have a script that prints the current date and time in JavaScript, but the DATE is always wrong. Here is the code:
27 A...
Get specific ArrayList item
How can I get a specific item from this ArrayList ? mainList[3] ?
8 Answers
8
...
How can I match on an attribute that contains a certain string?
I am having a problem selecting nodes by attribute when the attributes contains more than one word. For example:
10 Answer...
Relative frequencies / proportions with dplyr
Suppose I want to calculate the proportion of different values within each group. For example, using the mtcars data, how do I calculate the relative frequency of number of gears by am (automatic/manual) in one go with dplyr ?
...
Database: To delete or not to delete records
I don't think I am the only person wondering about this. What do you usually practice about database behavior? Do you prefer to delete a record from the database physically? Or is it better to just flag the record with a "deleted" flag or a boolean column to denote the record is active or inactive?
...
Browse the files created on a device by the iOS application I'm developing, on workstation?
I'm developing an IOS app that creates files on the device, e.g. with NSKeyedArchiver .
6 Answers
...
How do I move a file with Ruby?
...
You can use FileUtils to do this.
#!/usr/bin/env ruby
require 'fileutils'
FileUtils.mv('/tmp/your_file', '/opt/new/location/your_file')
Remember; if you are moving across partitions, "mv" will copy the file to new destination and unlink the source path.
...
Finding ALL duplicate rows, including “elements with smaller subscripts”
R's duplicated returns a vector showing whether each element of a vector or data frame is a duplicate of an element with a smaller subscript. So if rows 3, 4, and 5 of a 5-row data frame are the same, duplicated will give me the vector
...
There is no ViewData item of type 'IEnumerable' that has the key 'xxx'
...his on Stack Overflow but none with an answer that seem to fix the problem in my current situation.
10 Answers
...
Why does mongoose always add an s to the end of my collection name
For example, this code results in a collection called "datas" being created
8 Answers
...