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List comprehension: Returning two (or more) items for each item
...: x ** 2
>>> list(chain.from_iterable((f(x), g(x)) for x in range(3)))
[2, 0, 3, 1, 4, 4]
Timings:
from timeit import timeit
f = lambda x: x + 2
g = lambda x: x ** 2
def fg(x):
yield f(x)
yield g(x)
print timeit(stmt='list(chain.from_iterable((f(x), g(x)) for x in range(3)))',...
What's the difference between RANK() and DENSE_RANK() functions in oracle?
... assigned the same rank, with the next ranking(s) skipped. So, if you have 3 items at rank 2, the next rank listed would be ranked 5.
DENSE_RANK again gives you the ranking within your ordered partition, but the ranks are consecutive. No ranks are skipped if there are ranks with multiple items.
As...
Python pandas Filtering out nan from a data selection of a column of strings
...NaN:
In [87]:
nms
Out[87]:
movie name rating
0 thg John 3
1 thg NaN 4
3 mol Graham NaN
4 lob NaN NaN
5 lob NaN NaN
[5 rows x 3 columns]
In [89]:
nms = nms.dropna(thresh=2)
In [90]:
nms[nms.name.notnull()]
Out[90]:
movie name rating
0...
Integrate ZXing in Android Studio
...
234
I was integrating ZXING into an Android application and there were no good sources for the inpu...
How can I obtain the element-wise logical NOT of a pandas Series?
... True, False, True])
In [8]: ~s
Out[8]:
0 False
1 False
2 True
3 False
dtype: bool
Using Python2.7, NumPy 1.8.0, Pandas 0.13.1:
In [119]: s = pd.Series([True, True, False, True]*10000)
In [10]: %timeit np.invert(s)
10000 loops, best of 3: 91.8 µs per loop
In [11]: %timeit ~s
10...
Can Java 8 code be compiled to run on Java 7 JVM?
...
answered Mar 18 '14 at 22:30
JesperEJesperE
58.6k1515 gold badges129129 silver badges188188 bronze badges
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Rails mapping array of hashes onto single hash
...
163
You could compose Enumerable#reduce and Hash#merge to accomplish what you want.
input = [{"test...
How to remove last n characters from every element in the R vector
...rame("data"=char_array,"data2"=1:4)
a$data = substr(a$data,1,nchar(a$data)-3)
a should now contain:
data data2
1 foo_ 1
2 bar_ 2
3 ap 3
4 b 4
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How to convert a table to a data frame
...
324
I figured it out already:
as.data.frame.matrix(mytable)
does what I need -- apparently, th...