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Pandas dataframe get first row of each group
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>>> df.groupby('id').first()
value
id
1 first
2 first
3 first
4 second
5 first
6 first
7 fourth
If you need id as column:
>>> df.groupby('id').first().reset_index()
id value
0 1 first
1 2 first
2 3 first
3 4 seco...
Best way of returning a random boolean value
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edited Aug 23 '15 at 7:45
answered Nov 4 '11 at 16:43
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C# 5 async CTP: why is internal “state” set to 0 in generated code before EndAwait call?
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71
Okay, I finally have a real answer. I sort of worked it out on my own, but only after Lucian Wis...
Java String - See if a string contains only numbers and not letters
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17 Answers
17
Active
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Why is GHC so large/big?
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188
It's a bit silly really. Every library that comes with GHC is provided in no less than 4 flav...
Is there a way to list pip dependencies/requirements?
... so I am providing an updated answer.
This was tested with pip versions 8.1.2, 9.0.1, 10.0.1, and 18.1.
To get the output without cluttering your current directory on Linux use
pip download [package] -d /tmp --no-binary :all: -v
-d tells pip the directory that download should put files in.
Bet...
How to get different colored lines for different plots in a single figure?
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E.g.:
import matplotlib.pyplot as plt
import numpy as np
x = np.arange(10)
plt.plot(x, x)
plt.plot(x, 2 * x)
plt.plot(x, 3 * x)
plt.plot(x, 4 * x)
plt.show()
And, as you may already know, you can easily add a legend:
import matplotlib.pyplot as plt
import numpy as np
x = np.arange(10)
pl...
Does Python support short-circuiting?
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318
Yep, both and and or operators short-circuit -- see the docs.
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What does the constant 0.0039215689 represent?
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0.0039215689 is approximately equal to 1/255.
Seeing that this is OpenGL, performance is probably important. So it's probably safe to guess that this was done for performance reasons.
Multiplying by the reciprocal is faster than r...