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Best way to test for a variable's existence in PHP; isset() is clearly broken
From the isset() docs :
17 Answers
17
...
Create an empty list in python with certain size
...uld still fail, as our list has only 10 elements.
range(x) creates a list from [0, 1, 2, ... x-1]
# 2.X only. Use list(range(10)) in 3.X.
>>> l = range(10)
>>> l
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
Using a function to create a list:
>>> def display():
... s1 = []
... ...
How to drop rows of Pandas DataFrame whose value in a certain column is NaN
...e missing data, including dropna(), is built into pandas explicitly. Aside from potentially improved performance over doing it manually, these functions also come with a variety of options which may be useful.
In [24]: df = pd.DataFrame(np.random.randn(10,3))
In [25]: df.iloc[::2,0] = np.nan; df....
Computed read-only property vs function in Swift
...when actual work is being done. Maybe something has to be computed or read from disk or from a database: In this case I use a function, even when only a simple value is returned. That way I can easily see whether a call is cheap (properties) or possibly expensive (functions).
We will probably get ...
How to convert List to int[] in Java? [duplicate]
...rticular:
List<T>.toArray won't work because there's no conversion from Integer to int
You can't use int as a type argument for generics, so it would have to be an int-specific method (or one which used reflection to do nasty trickery).
I believe there are libraries which have autogenerate...
How do I clone a Django model instance object and save it to the database?
...objects one by one. If you don't want the call to the database, just do:
from copy import deepcopy
new_instance = deepcopy(object_you_want_copied)
new_instance.id = None
new_instance.save()
It does the same thing as some of these other answers, but it doesn't make the database call to retrieve ...
Switch on Enum in Java [duplicate]
...
You definitely can switch on enums. An example posted from the Java tutorials.
public enum Day {
SUNDAY, MONDAY, TUESDAY, WEDNESDAY,
THURSDAY, FRIDAY, SATURDAY
}
public class EnumTest {
Day day;
public EnumTest(Day day) {
this.day = day;
}
p...
The most accurate way to check JS object's type?
...
|| (cache[key] = key.slice(8, -1).toLowerCase()); // get XXXX from [object XXXX], and cache it
};
}(this));
use as:
type(function(){}); // -> "function"
type([1, 2, 3]); // -> "array"
type(new Date()); // -> "date"
type({}); // -> "object"
...
Javascript - Track mouse position
...'t available and clientX/Y are,
// calculate pageX/Y - logic taken from jQuery.
// (This is to support old IE)
if (event.pageX == null && event.clientX != null) {
eventDoc = (event.target && event.target.ownerDocument) || document;
doc ...
How to “EXPIRE” the “HSET” child key in redis?
...e useful in all scenarios and the performance characteristics might differ from the expected ones. Still worth mentioning:
When having a hash, the structure basically looks like:
hash_top_key
- child_key_1 -> some_value
- child_key_2 -> some_value
...
- child_key_n -> some_value
...