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List comprehension: Returning two (or more) items for each item
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>>> from itertools import chain
>>> f = lambda x: x + 2
>>> g = lambda x: 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):
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~x + ~y == ~(x + y) is always false?
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Assume for the sake of contradiction that there exists some x and some y (mod 2n) such that
~(x+y) == ~x + ~y
By two's complement*, we know that,
-x == ~x + 1
<==> -1 == ~x + x
Noting this result, we have,
~(x+y) == ~x + ~y
<==> ~(x+y) + (x+...
Real life example, when to use OUTER / CROSS APPLY in SQL
...SS / OUTER APPLY with a colleague and we're struggling to find real life examples of where to use them.
4 Answers
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Renaming columns in pandas
...can do something like: new_columns = df.columns.values; new_columns[0] = 'XX'; df.columns = new_columns
– cd98
Nov 20 '13 at 14:18
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What is x after “x = x++”?
What happens (behind the curtains) when this is executed?
17 Answers
17
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Rename specific column(s) in pandas
...taframe called data . How would I rename the only one column header? For example gdp to log(gdp) ?
5 Answers
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Lambda function in list comprehensions
... of those in a list. To make it equivalent to the first you need:
[(lambda x: x*x)(x) for x in range(10)]
Or better yet:
[x*x for x in range(10)]
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Changing the resolution of a VNC session in linux [closed]
I use VNC to connect to a Linux workstation at work. At work I have a 20" monitor that runs at 1600x1200, while at home I use my laptop with its resolution of 1440x900.
If I set the vncserver to run at 1440x900 I miss out on a lot of space on my monitor, whereas if I set it to run at 1600x1200 it d...
Get unique values from a list in python [duplicate]
...eginning, instead of a list. Then your code should be:
output = set()
for x in trends:
output.add(x)
print(output)
As it has been pointed out, sets do not maintain the original order. If you need that, you should look for an ordered set implementation (see this question for more).
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How to do exponential and logarithmic curve fitting in Python? I found only polynomial fitting
...to compare which line describes it best (polynomials of different orders, exponential or logarithmic).
7 Answers
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