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How can I check whether a numpy array is empty or not?
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You can always take a look at the .size attribute. It is defined as an integer, and is zero (0) when there are no elements in the array:
import numpy as np
a = np.array([])
if a.size == 0:
# Do something when `a` is empty
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Python: most idiomatic way to convert None to empty string?
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If you actually want your function to behave like the str() built-in, but return an empty string when the argument is None, do this:
def xstr(s):
if s is None:
return ''
return str(s)
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How do I change the background color with JavaScript?
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For answering literally: the question was about changing the color of the background, not all of the background.
– Wolf
Jul 23 '15 at 11:31
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Kotlin secondary constructor
...tructors in Kotlin since these constructors are necessary sometimes, especially when working with Java frameworks and extending Java classes. Hope you'll get them back soon.
– Michael
Jul 17 '14 at 7:46
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Ruby on Rails: Where to define global constants?
...h are accessible from everywhere in an initializer like in the following example. This is probably the best place, if your colours are really global and used in more than one model context.
# put this into config/initializers/my_constants.rb
COLOURS = ['white', 'blue'].freeze
Note: when we define...
How do I get user IP address in django?
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You can use django-ipware which supports Python 2 & 3 and handles IPv4 & IPv6.
Install:
pip install django-ipware
Simple Usage:
# In a view or a middleware where the `request` object is available
from ipware import get_client_ip
ip, is_routable = get_client_ip(r...
Is there a reason that we cannot iterate on “reverse Range” in ruby?
...its start and end, not by its contents. "Iterating" over a range doesn't really make sense in a general case. Consider, for example, how you would "iterate" over the range produced by two dates. Would you iterate by day? by month? by year? by week? It's not well-defined. IMO, the fact that it's allo...
Rails: How to reference images in CSS within Rails 4
... don't have the proper name adjusted. Here's what I mean. I have a file called logo.png. Yet when it shows up on heroku it is viewed as:
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Difference between null and empty (“”) Java String
... String("");
System.out.println(a==b);
That would output false because I allocated two different objects, and a and b point to different objects.
However, a.equals(b) in this case would return true, because equals for Strings will return true if and only if the argument String is not null and rep...
Changing the selected option of an HTML Select element
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None of the examples using jquery in here are actually correct as they will leave the select displaying the first entry even though value has been changed.
The right way to select Alaska and have the select show the right item as selected...