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Sorting multiple keys with Unix sort
I have potentially large files that need to be sorted by 1-n keys. Some of these keys might be numeric and some of them might not be. This is a fixed-width columnar file so there are no delimiters.
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Why is it slower to iterate over a small string than a small list?
...ser to 70% (or more) once a lot of the overhead is removed, for Python 2.
Object creation is not at fault. Neither method creates a new object, as one-character strings are cached.
The difference is unobvious, but is likely created from a greater number of checks on string indexing, with regards to ...
Take the content of a list and append it to another list
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You probably want
list2.extend(list1)
instead of
list2.append(list1)
Here's the difference:
>>> a = range(5)
>>> b = range(3)
>>> c = range(2)
>>> b.append(a)
>>> b
[0, 1, 2, [0, 1...
How can I create a copy of an object in Python?
I would like to create a copy of an object. I want the new object to possess all properties of the old object (values of the fields). But I want to have independent objects. So, if I change values of the fields of the new object, the old object should not be affected by that.
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What's the difference between deadlock and livelock?
Can somebody please explain with examples (of code) what is the difference between deadlock and livelock ?
7 Answers
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Get list from pandas DataFrame column headers
...rame will come from user input so I won't know how many columns there will be or what they will be called.
19 Answers
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Git submodule update
I'm not clear on what the following means (from the Git submodule update documentation):
4 Answers
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Concatenating two std::vectors
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vector1.insert( vector1.end(), vector2.begin(), vector2.end() );
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jQuery: select an element's class and id at the same time?
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Tintin81
8,5361717 gold badges6262 silver badges131131 bronze badges
answered Dec 22 '09 at 5:24
cletuscletus
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PostgreSQL return result set as JSON array?
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TL;DR
SELECT json_agg(t) FROM t
for a JSON array of objects, and
SELECT
json_build_object(
'a', json_agg(t.a),
'b', json_agg(t.b)
)
FROM t
for a JSON object of arrays.
List of objects
This section describes how to generate a JSON array of objects, ...