大约有 47,000 项符合查询结果（耗时：0.0530秒） [XML]
How to convert a data frame column to numeric type?
... that you should apply transform function in order to complete your task.
Now I'm about to demonstrate certain "conversion anomaly":
# create dummy data.frame
d <- data.frame(char = letters[1:5],
fake_char = as.character(1:5),
fac = factor(1:5),
...
constant pointer vs pointer on a constant value [duplicate]
...
Now that you know the difference between char * const a and const char * a. Many times we get confused if its a constant pointer or pointer to a constant variable.
How to read it? Follow the below simple step to identify bet...
Check if a string contains a string in C++
...proach" << std::endl;
start = high_resolution_clock::now();
for(size_t i=0; i<haystacksCount; ++i)
{
if(haystacks[i].find(needle) != std::string::npos)
{
sink = !s...
Does Dart support enumerations?
... constants within the class are compile time constants, and this class can now be used in, for example, switch statements:
var a = Fruit.APPLE;
switch (a) {
case Fruit.APPLE:
print('Yes!');
break;
}
share
...
How to detect online/offline event cross-browser?
...k when the user
follows links or when a script
requests a remote page (or knows that
such an attempt would fail), and must
return true otherwise.
Finally, the spec notes:
This attribute is inherently
unreliable. A computer can be
connected to a network without having
Internet access.
...
How to read and write into file using JavaScript?
...ion on the Javascript File class
Edit: That link was to the Sun docs that now have been moved by Oracle.
To keep up with the times here's the node.js documentation for the FileSystem class: http://nodejs.org/docs/latest/api/fs.html
Edit(2): You can read files client side now with HTML5: http://ww...
Find the number of downloads for a particular app in apple appstore [closed]
...o a market research on specific type of apps. so is there a way for me to know the download count of the app / any app.
4 A...
How to create a GUID/UUID using iOS
...ns the Unique ID of your iPhone.
EDIT: -[UIDevice uniqueIdentifier] is now deprecated and apps are being rejected from the App Store for using it. The method below is now the preferred approach.
If you need to create several UUID, just use this method (with ARC):
+ (NSString *)GetUUID
{
CFU...
Optional Methods in Java Interface
...fiableList, and
ModifiableMap. What was previously a simple hierarchy is now a messy
heterarchy. Also, you need a new Iterator interface for use with
unmodifiable Collections, that does not contain the remove operation.
Now can you do away with UnsupportedOperationException? Unfortunately
...
Greenlet Vs. Threads
...lution with multiprocessing to achieve higher throughput? 2)I still don't know why ever use threads? Can we consider them as a naive and basic implementation of concurrency in python standard library?
– Rsh
Mar 24 '13 at 8:23
...