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Remove all the elements that occur in one list from another
...have two lists, l1 and l2 . I want to perform l1 - l2 , which returns all elements of l1 not in l2 .
7 Answers
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Visual Studio debugging “quick watch” tool and lambda expressions
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Lambda expressions, like anonymous methods, are actually very complex beasts. Even if we rule out Expression (.NET 3.5), that still leaves a lot of complexity, not least being captured variables, which fundamentally re-structure the code that uses them (what you think of as va...
How do you use the ? : (conditional) operator in JavaScript?
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This is a one-line shorthand for an if-else statement. It's called the conditional operator.1
Here is an example of code that could be shortened with the conditional operator:
var userType;
if (userIsYoungerThan18) {
userType = "Minor";
} else {
userType = "Adult";
}
if (userIsY...
How to access environment variable values?
...os.environ
import os
print(os.environ['HOME'])
Or you can see a list of all the environment variables using:
os.environ
As sometimes you might need to see a complete list!
# using get will return `None` if a key is not present rather than raise a `KeyError`
print(os.environ.get('KEY_THAT_MIGH...
Possible to change where Android Virtual Devices are saved?
... \.android" by default. Is there any way to change this behavior? I have all of the other components saved in a directory on a separate partition and would like everything to be consolidated. Obviously not a huge deal but does anyone here know a workaround for this?
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Any way to select without causing locking in MySQL?
...ere are locks and opposing to InnoDB those locks are table locks, blocking all requested WRITE locks and all subsequent queries during execution. The original question appears to be about InnoDB though and isolation levels are non-existent for MyISAM too - the docs for the SET TRANSACTION statement ...
How can I check for an empty/undefined/null string in JavaScript?
...n do
if (strValue) {
//do something
}
If you need to check specifically for an empty string over null, I would think checking against "" is your best bet, using the === operator (so that you know that it is, in fact, a string you're comparing against).
if (strValue === "") {
//...
}
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Python speed testing - Time Difference - milliseconds
...e timedelta! For timing purposes always use c.total_seconds().
You can do all sorts of maths with datetime.timedelta, eg:
>>> c / 10
datetime.timedelta(0, 0, 431654)
It might be more useful to look at CPU time instead of wallclock time though ... that's operating system dependant though...
Why is there no Tree class in .NET?
...BCL. I suspect this is because the choice of whether to use a tree is typically an implementation detail and is otherwise an unconventional way to access data. That is, you don't say, "binary-search-for element #37"; instead, you say, "get me element #37".
But have you taken a look at C5? It's supe...
End of support for python 2.7?
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@Basic welll... that share is pretty slim: 25 over all python versions (4% code exec): cvedetails.com/product/18230/Python-Python.html?vendor_id=10210 vs php with 408 (27% code exec): cvedetails.com/product/128/PHP-PHP.html?vendor_id=74 or Java with 438 (3% code exec): cvede...