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Swapping column values in MySQL
...t. This method doesn't swap the values if one of them is NULL. Use method #3 that doesn't have this limitation.
UPDATE swap_test SET x=y, y=@temp WHERE (@temp:=x) IS NOT NULL;
This method was offered by Dipin in, yet again, the comments of http://beerpla.net/2009/02/17/swapping-column-values-in-mys...
Remove last item from array
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edited Aug 3 at 10:48
CroMagnon
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How to create the most compact mapping n → isprime(n) up to a limit N?
...number with one bit e.g. for the given range of numbers (1, 10], starts at 3: 1110
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Apply pandas function to column to create multiple new columns?
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PHP best way to MD5 multi-dimensional array?
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Normalize data in pandas
... df
Out[92]:
a b c d
A -0.488816 0.863769 4.325608 -4.721202
B -11.937097 2.993993 -12.916784 -1.086236
C -5.569493 4.672679 -2.168464 -9.315900
D 8.892368 0.932785 4.535396 0.598124
In [93]: df_norm = (df - df.mean()) / (df.max() - df.min())
In [9...
Automatically expanding an R factor into a collection of 1/0 indicator variables for every factor le
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Use the model.matrix function:
model.matrix( ~ Species - 1, data=iris )
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How to avoid reinstalling packages when building Docker image for Python projects?
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Try to build a Dockerfile which looks something like this:
FROM my/base
WORKDIR /srv
ADD ./requ...
What's the best way to send a signal to all members of a process group?
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Auto-center map with multiple markers in Google Maps API v3
This is what I use to display a map with 3 pins/markers:
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