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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...
C++ map access discards qualifiers (const)
...k up a key without modifying the map.
find() returns an iterator, or const_iterator to an std::pair containing both the key (.first) and the value (.second).
In C++11, you could also use at() for std::map. If element doesn't exist the function throws a std::out_of_range exception, in contrast to o...
Chain-calling parent initialisers in python [duplicate]
... B inheriting from A, class C inheriting from B. What is a generic way to call a parent class initialiser in an initialiser? If this still sounds too vague, here's some code.
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Sorting Python list based on the length of the string
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def lensort(list_1):
list_2=[];list_3=[]
for i in list_1:
list_2.append([i,len(i)])
list_2.sort(key = lambda x : x[1])
for i in list_2:
list_3.append(i[0])
return list_3
This works for me!
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undefined reference to `__android_log_print'
...sary. Please accept the other answer instead.
– Jeff Allen
Jun 21 '13 at 11:23
5
If using the new...
How to replace captured groups only?
...ding and following text:
str.replace(/(.*name="\w+)(\d+)(\w+".*)/, "$1!NEW_ID!$3")
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Zip lists in Python
...x. list, string, tuple, dictionary)
Output (list)
1st tuple = (element_1 of numbers, element_1 of letters)
2nd tuple = (e_2 numbers, e_2 letters)
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n-th tuple = (e_n numbers, e_n letters)
List of n tuples: n is the length of the shortest argument (input)
len(numbers) =...
How do I set a conditional breakpoint in gdb, when char* x points to a string whose value equals “he
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This method can have side effects. $_streq method from @tlwhitec is better.
– rools
Apr 14 '19 at 14:08
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How do I add a path to PYTHONPATH in virtualenv
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You can usually avoid having to do anything with PYTHONPATH by using .pth files. Just put a file with a .pth extension (any basename works) in your virtualenv's site-packages folder, e.g. lib\python2.7\site-packages, with the absolute p...
putting current class as return type annotation [duplicate]
...e. Instead, they are preserved in __annotations__ in string form. This is called Postponed Evaluation of Annotations, introduced in PEP 563.
Also note:
Deprecation policy
Starting with Python 3.7, a __future__ import is required to use the
described functionality. No warnings are raised...