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How to reshape data from long to wide format
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And, as of data.table v1.9.6 we can cast on multiple columns
## add an extra column
dat1[, value2 := value * 2]
## cast multiple value columns
dcast(dat1, name ~ numbers, value.var = c("value", "value2"))
# name value_1 value_2 value_3 value_4 value2_1 value2_2 value2_3 ...
How can you determine a point is between two other points on a line segment?
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Yes, the extra parenthesis is just a typo. 4 years have passed before someone said something. :)
– Cyrille Ka
Nov 22 '12 at 3:36
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Iterate a list as pair (current, next) in Python
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This should really be the answer, it doesn't rely on any extra imports and works great.
– jamescampbell
Sep 27 '18 at 13:09
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What's the purpose of using braces (i.e. {}) for a single-line if or loop?
...d) (b*b) - ((4*a)*c)?
Some precedences are obvious (or should be), and the extra parentheses
just add to confusion. (On the other hand, you _should_ use the
parentheses in less obvious cases, even if you know that they're not
needed.)
Sort of. There are two wide spread conventions for formatting...
Merge 2 arrays of objects
...mplexity as @YOU's answer, except that this is much slower (largely due to extra function calls and the fact the YOU's answer exploits the JS associative arrays trick to find items with O(1) lookup). This is besides the fact that you need to bring an additional library.
– Mrch...
How to define @Value as optional
...r example was @Value("${myValue:DEFAULT}").
You are not limited to plain strings as default values. You can use SPEL expressions, and a simple SPEL expression to return null is:
@Value("${myValue:#{null}}")
share
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How to make grep only match if the entire line matches?
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grep -Fx ABB.log a.tmp
From the grep man page:
-F, --fixed-strings
Interpret PATTERN as a (list of) fixed strings
-x, --line-regexp
Select only those matches that exactly match the whole line.
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“The file ”MyApp.app“ couldn't be opened because you don't have permission to view it” when running
...nce:
<key>CFBundleDevelopmentRegion</key>
<string>en</string>
<key>CFBundleExecutable</key>
- <string>iOS</string>
+ <string>${EXECUTABLE_NAME}</string>
<key>CFBundleIdentifier</key>
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How can I use speech recognition without the annoying dialog in android phones
...rsionCallback {
override fun onSuccess(result: String) {
sttOutput.text = result
}
override fun onCompletion() {
}
override fu...
MySQL JOIN the most recent row only?
...private int id;
private CustomerData currentData;
public Customer(String title, String forename, String surname)
{
this.update(title, forename, surname);
}
public void update(String title, String forename, String surname)
{
this.currentData = new CustomerDat...