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Using getopts to process long and short command line options
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32 Answers
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When is SQLiteOpenHelper onCreate() / onUpgrade() run?
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edited Apr 27 at 6:55
community wiki
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Overload constructor for Scala's Case Classes?
In Scala 2.8 is there a way to overload constructors of a case class?
2 Answers
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What's valid and what's not in a URI query?
...he current standard for generic URIs is RFC 3986, which has this to say:
2.2. Reserved Characters
URIs include components and subcomponents that are delimited by characters in the "reserved" set. These characters are called "reserved" because they may (or may not) be defined as delimiters by the g...
How to split a delimited string in Ruby and convert it to an array?
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>> "1,2,3,4".split(",")
=> ["1", "2", "3", "4"]
Or for integers:
>> "1,2,3,4".split(",").map { |s| s.to_i }
=> [1, 2, 3, 4]
Or for later versions of ruby (>= 1.9 - as pointed out by Alex):
>> "1,2,3,4".sp...
Ignoring new fields on JSON objects using Jackson [duplicate]
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12 Answers
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What's the cleanest way of applying map() to a dictionary in Swift?
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285
Swift 4+
Good news! Swift 4 includes a mapValues(_:) method which constructs a copy of a dict...
How to get first element in a list of tuples?
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12 Answers
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Split string every nth character?
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>>> line = '1234567890'
>>> n = 2
>>> [line[i:i+n] for i in range(0, len(line), n)]
['12', '34', '56', '78', '90']
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count the frequency that a value occurs in a dataframe column
...ame({'a':list('abssbab')})
df.groupby('a').count()
Out[37]:
a
a
a 2
b 3
s 2
[3 rows x 1 columns]
See the online docs: http://pandas.pydata.org/pandas-docs/stable/groupby.html
Also value_counts() as @DSM has commented, many ways to skin a cat here
In [38]:
df['a'].value_counts()
Out[...