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In Python, what is the difference between “.append()” and “+= []”?
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In general case append will add one item to the list, while += will copy all elements of right-hand-side list into the left-hand-side list.
Update: perf analysis
Comparing bytecodes we can assume that append version wastes cycles in LOAD_ATTR + CALL_FUNCTION, and += version -- in BUILD_LIST. App...
Pass Variables by Reference in Javascript
... it means that it's possible to pass a simple variable in such a way as to allow a function to modify that value in the calling context. So:
function swap(a, b) {
var tmp = a;
a = b;
b = tmp; //assign tmp to b
}
var x = 1, y = 2;
swap(x, y);
alert("x is " + x + ", y is " + y); // "...
Foreign keys in mongo?
...his:
class Student
include Mongoid::Document
field :name
embeds_many :addresses
embeds_many :scores
end
class Address
include Mongoid::Document
field :address
field :city
field :state
field :postalCode
embedded_in :student
end
class Score
include Mongoi...
MySQL OPTIMIZE all tables?
...ZE TABLE command which can be used to reclaim unused space in a MySQL install. Is there a way (built-in command or common stored procedure) to run this optimization for every table in the database and/or server install, or is this something you'd have to script up yourself?
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How do I find numeric columns in Pandas?
Let's say df is a pandas DataFrame.
I would like to find all columns of numeric type.
Something like:
11 Answers
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Saving utf-8 texts in json.dumps as UTF8, not as \u escape sequence
...ure_ascii=False switch to json.dumps(), then encode the value to UTF-8 manually:
>>> json_string = json.dumps("ברי צקלה", ensure_ascii=False).encode('utf8')
>>> json_string
b'"\xd7\x91\xd7\xa8\xd7\x99 \xd7\xa6\xd7\xa7\xd7\x9c\xd7\x94"'
>>> print(json_string.decode(...
Rails: Open link in new tab (with 'link_to')
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The target: :_blank parameter should be a parameter of link_to, whereas you put it in image_tag parameters. Modify your code like this:
<%= link_to image_tag("facebook.png", class: :facebook_icon, alt: "Facebook"), "http://www.facebo...
@UniqueConstraint annotation in Java
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@Entity
@Table(uniqueConstraints={@UniqueConstraint(columnNames = {"id_1" , "id_2"})})
public class class_name {
@Id
@GeneratedValue
public Long id;
@NotNull
public Long id_1;
@NotNull
public Long id_2;
}
Hope it helped.
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Add a new item to a dictionary in Python [duplicate]
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default_data['item3'] = 3
Easy as py.
Another possible solution:
default_data.update({'item3': 3})
which is nice if you want to insert multiple items at once.
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Numeric for loop in Django templates
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I've used a simple technique that works nicely for small cases with no special tags and no additional context. Sometimes this comes in handy
{% for i in '0123456789'|make_list %}
{{ forloop.counter }}
{% endfor %}
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