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Python constructor and default value [duplicate]
...x2
Type "help", "copyright", "credits" or "license" for more information.
>>> class Foo:
... def __init__(self, x=[]):
... x.append(1)
...
>>> Foo.__init__.__defaults__
([],)
>>> f = Foo()
>>> Foo.__init__.__defaults__
([1],)
>>> f2 = Foo()
&...
How do we determine the number of days for a given month in python [duplicate]
...days. Could any one tell me which library I should use to determine the length of a given month.
3 Answers
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Inserting a string into a list without getting split into characters
...
Another option is using the overloaded + operator:
>>> l = ['hello','world']
>>> l = ['foo'] + l
>>> l
['foo', 'hello', 'world']
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How to auto-format code in Eclipse?
...
On Mac : ⌘ + ⇧ + F
(Alternatively you can press Format in Main Menu > Source)
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How do I convert a byte array to Base64 in Java?
...;
println(decoded) // Outputs "Hello"
For more info, see Base64.
Java < 8
Base64 is not bundled with Java versions less than 8. I recommend using Apache Commons Codec.
For direct byte arrays:
Base64 codec = new Base64();
byte[] encoded = codec.encode("Hello".getBytes());
println(new String(en...
Convert datetime to Unix timestamp and convert it back in python
...rt a python datetime to seconds since epoch you should do it explicitly:
>>> import datetime
>>> datetime.datetime(2012,04,01,0,0).strftime('%s')
'1333234800'
>>> (datetime.datetime(2012,04,01,0,0) - datetime.datetime(1970,1,1)).total_seconds()
1333238400.0
In Python 3....
Best way to convert strings to symbols in hash
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In Ruby >= 2.5 (docs) you can use:
my_hash.transform_keys(&:to_sym)
Using older Ruby version? Here is a one-liner that will copy the hash into a new one with the keys symbolized:
my_hash = my_hash.inject({}){|memo,(k,v)| me...
How to get numbers after decimal point?
...
Use modf:
>>> import math
>>> frac, whole = math.modf(2.5)
>>> frac
0.5
>>> whole
2.0
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What is the fastest way to check if a class has a function defined?
...checking for the key's existence is fast.
See timing comparisons below.
>>> class SomeClass():
... pass
...
>>> obj = SomeClass()
>>>
>>> getattr(obj, "invert_op", None)
>>>
>>> %timeit getattr(obj, "invert_op", None)
1000000 loops, bes...
When is “i += x” different from “i = i + x” in Python?
...ile immutable types, like int, will just not implement it.
For example:
>>> l1 = []
>>> l2 = l1
>>> l1 += [3]
>>> l2
[3]
Because l2 is the same object as l1, and you mutated l1, you also mutated l2.
But:
>>> l1 = []
>>> l2 = l1
>>>...