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Extract first item of each sublist
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You could use zip:
>>> lst=[[1,2,3],[11,12,13],[21,22,23]]
>>> zip(*lst)[0]
(1, 11, 21)
Or, Python 3 where zip does not produce a list:
>>> list(zip(*lst))[0]
(1, 11, 21)
Or,
>>> next(zip(*lst))
(1, 11, 21)
Or, (my favorite) use numpy:
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Simple regular expression for a decimal with a precision of 2
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answered Nov 21 '08 at 7:32
DocMaxDocMax
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Numpy: Divide each row by a vector element
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edited Nov 21 '19 at 16:13
answered Mar 21 '19 at 4:52
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Using Razor, how do I render a Boolean to a JavaScript variable?
...lete the code.
– taylorswiftfan
Apr 21 at 19:11
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leading zeros in rails
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answered Apr 27 '11 at 21:02
Jon GauthierJon Gauthier
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What's the difference between “mod” and “remainder”?
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There is a difference between modulus and remainder. For example:
-21 mod 4 is 3 because -21 + 4 x 6 is 3.
But -21 divided by 4 gives -5 with a remainder of -1.
For positive values, there is no difference.
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Java recursive Fibonacci sequence
... = 3
fibonacci(5) = 3+2 = 5
And from fibonacci sequence 0,1,1,2,3,5,8,13,21.... we can see that for 5th element the fibonacci sequence returns 5.
See here for Recursion Tutorial.
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How to find the installed pandas version
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LANG: en_US.UTF-8
pandas: 0.15.2-113-g5531341
nose: 1.3.1
Cython: 0.21.1
numpy: 1.8.2
scipy: 0.14.0.dev-371b4ff
statsmodels: 0.6.0.dev-a738b4f
IPython: 2.0.0-dev
sphinx: 1.2.2
patsy: 0.3.0
dateutil: 1.5
pytz: 2012c
bottleneck: None
tables: 3.1.1
numexpr: 2.2.2
matplotlib: 1.4.2
openpyxl: None...
How to form tuple column from two columns in Pandas
... JungDale Jung
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How to access pandas groupby dataframe by key
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You can use the get_group method:
In [21]: gb.get_group('foo')
Out[21]:
A B C
0 foo 1.624345 5
2 foo -0.528172 11
4 foo 0.865408 14
Note: This doesn't require creating an intermediary dictionary / copy of every subdataframe for every gr...