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Group a list of objects by an attribute : Java
... list);
} else {
hashMap.get(locationId).add(student);
}
If you want all the student with particular location details then you can use this:
hashMap.get(locationId);
which will get you all the students with the same the location ID.
...
Replacing NAs with latest non-NA value
... Use na.locf(cz, na.rm=FALSE) to keep leading NA.
– BallpointBen
May 17 '18 at 16:21
1
@Ballpoint...
How do I check if a variable exists?
...have nested functions, variables in outer scopes. If you want to check for all of them, you're probably best off triggering NameError after all.
– Petr Viktorin
Jun 10 '14 at 20:18
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How do I wrap a selection with an HTML tag in Visual Studio?
... as well, but you must have the "ASP.NET and Web Development" workload installed.
Example
Shift+Alt+W > p > Enter
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How do I calculate the date six months from the current date using the datetime Python module?
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@sliders_alpha You need to install the python-dateutil package (pip install python-dateutil)
– poiuytrez
Nov 19 '13 at 15:29
19
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Check if a value is within a range of numbers
...u're asking a question about numeric comparisons, so regular expressions really have nothing to do with the issue. You don't need "multiple if" statements to do it, either:
if (x >= 0.001 && x <= 0.009) {
// something
}
You could write yourself a "between()" function:
function b...
How can I get the max (or min) value in a vector?
... Yes you can. The standard library algorithms have been designed to generically work on iterators. Pointers are iterators too.
– sehe
Aug 14 '14 at 9:48
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Using global variables in a function
...ce global variables are so dangerous, Python wants to make sure that you really know that's what you're playing with by explicitly requiring the global keyword.
See other answers if you want to share a global variable across modules.
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Django queries - id vs pk
...ry key field i.e. you don't need to care whether the primary key field is called id or object_id or whatever.
It also provides more consistency if you have models with different primary key fields.
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How do I add files without dots in them (all extension-less files) to the gitignore file?
...**/
!*.*
That gitignore exclusion rule (a negated pattern) should ignore all files, except the ones with an extension.
As mentioned below by Mad Physicist, the rule is:
It is not possible to re-include a file if a parent directory of that file is excluded. (*)
(*: unless certain conditions are m...