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Logical operators for boolean indexing in Pandas
...l-and since only x or y can be returned. In contrast, x & y triggers x.__and__(y) and the __and__ method can be defined to return anything we like.
– unutbu
Apr 15 '16 at 22:58
...
How to access the ith column of a NumPy multidimensional array?
...0,2]] = something would modify test, and not create another array. But copy_test = test[:, [0,2]] does in fact create a copy as you say.
– Akavall
Apr 11 '14 at 16:19
...
List directory tree structure in python?
...
Here's a function to do that with formatting:
import os
def list_files(startpath):
for root, dirs, files in os.walk(startpath):
level = root.replace(startpath, '').count(os.sep)
indent = ' ' * 4 * (level)
print('{}{}/'.format(indent, os.path.basename(root)))
...
Python - Create a list with initial capacity
...ux
Perhaps you could avoid the list by using a generator instead:
def my_things():
while foo:
#baz
yield bar
#qux
for thing in my_things():
# do something with thing
This way, the list isn't every stored all in memory at all, merely generated as needed.
...
How do I determine the size of an object in Python?
...rieve the size and would cause a
TypeError.
getsizeof calls the object’s
__sizeof__ method and adds an additional garbage collector overhead
if the object is managed by the
garbage collector.
See recursive sizeof recipe for an example of using getsizeof() recursively to find the size of containers...
In Python, how do I read the exif data for an image?
...
You can use the _getexif() protected method of a PIL Image.
import PIL.Image
img = PIL.Image.open('img.jpg')
exif_data = img._getexif()
This should give you a dictionary indexed by EXIF numeric tags. If you want the dictionary indexed by t...
Does Python have an ordered set?
... the signature for .union doesn't match that of set, but since it includes __or__ something similar can easily be added:
@staticmethod
def union(*sets):
union = OrderedSet()
union.union(*sets)
return union
def union(self, *sets):
for set in sets:
self |= set
...
Why does GCC generate 15-20% faster code if I optimize for size instead of speed?
...ssembly from gcc-4.6.4 -Os (executes in 0.709 secs):
00000000004004d2 <_ZL3addRKiS0_.isra.0>:
4004d2: 8d 04 37 lea eax,[rdi+rsi*1]
4004d5: c3 ret
00000000004004d6 <_ZL4workii>:
4004d6: 41 55 push r13
4...
How to implement an ordered, default dict? [duplicate]
...eredDict):
# Source: http://stackoverflow.com/a/6190500/562769
def __init__(self, default_factory=None, *a, **kw):
if (default_factory is not None and
not isinstance(default_factory, Callable)):
raise TypeError('first argument must be callable')
Ordered...
What is the most efficient string concatenation method in python?
...iven the test case from mkoistinen's answer, having strings
domain = 'some_really_long_example.com'
lang = 'en'
path = 'some/really/long/path/'
The contenders are
f'http://{domain}/{lang}/{path}' - 0.151 µs
'http://%s/%s/%s' % (domain, lang, path) - 0.321 µs
'http://' + domain + '/' + lang ...