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Pandas dataframe get first row of each group
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248
>>> df.groupby('id').first()
value
id
1 first
2 first
3 first
4...
Rotating videos with FFmpeg
... pass:
0 = 90CounterCLockwise and Vertical Flip (default)
1 = 90Clockwise
2 = 90CounterClockwise
3 = 90Clockwise and Vertical Flip
Use -vf "transpose=2,transpose=2" for 180 degrees.
Make sure you use a recent ffmpeg version from here (a static build will work fine).
Note that this will re-encod...
How can I obtain an 'unbalanced' grid of ggplots?
..., arrangeGrob(p,p,p, heights=c(3/4, 1/4, 1/4), ncol=1),
ncol=2)
Edit (07/2015): with v>2.0.0 you can use the layout_matrix argument,
grid.arrange(p,p,p,p, layout_matrix = cbind(c(1,1,1), c(2,3,4)))
shar...
MongoDB logging all queries
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268
You can log all queries:
$ mongo
MongoDB shell version: 2.4.9
connecting to: test
> use my...
How does Python 2 compare string and int? Why do lists compare as greater than numbers, and tuples g
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2 Answers
2
Active
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How do you know when to use fold-left and when to use fold-right?
...re, you use a left fold. Example (haskell-style pseudocode)
foldl (-) [1, 2, 3] == (1 - 2) - 3 == 1 - 2 - 3 // - is left-associative
If your operator is right-associative (right fold), the parentheses would be set like this:
A x (B x (C x D))
Example: Cons-Operator
foldr (:) [] [1, 2, 3] == 1...
What does the “map” method do in Ruby?
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432
The map method takes an enumerable object and a block, and runs the block for each element, outp...
Autoreload of modules in IPython [duplicate]
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For IPython version 3.1, 4.x, and 5.x
%load_ext autoreload
%autoreload 2
Then your module will be auto-reloaded by default. This is the doc:
File: ...my/python/path/lib/python2.7/site-packages/IPython/extensions/autoreload.py
Docstring:
``autoreload`` is an IPython extension that reloa...
What does “|=” mean? (pipe equal operator)
...tic final int DEFAULT_SOUND = 1;
public static final int DEFAULT_VIBRATE = 2; // is the same than 1<<1 or 10 in binary
public static final int DEFAULT_LIGHTS = 4; // is the same than 1<<2 or 100 in binary
So you can use bit-wise OR to add flags
int myFlags = DEFAULT_SOUND | DEFAULT_VI...
Pretty printing JSON from Jackson 2.2's ObjectMapper
...and I can't seem to find the proper, non-deprecated way of doing this with 2.2. Even though I don't believe that code is absolutely necessary for this question, here's what I have right now:
...