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Fetch frame count with ffmpeg
...below.
ffprobe: Query the container
ffprobe -v error -select_streams v:0 -show_entries stream=nb_frames -of default=nokey=1:noprint_wrappers=1 input.mp4
This is a fast method.
Not all formats (such as Matroska) will report the number of frames resulting in the output of N/A. See the other met...
What does %~d0 mean in a Windows batch file?
...
The magic variables %n contains the arguments used to invoke the file: %0 is the path to the bat-file itself, %1 is the first argument after, %2 is the second and so on.
Since the arguments are often file paths, there is some additional syntax to extract parts of the path. ~d is drive, ~p is the...
Relative frequencies / proportions with dplyr
...n = n()) %>%
mutate(freq = n / sum(n))
# am gear n freq
# 1 0 3 15 0.7894737
# 2 0 4 4 0.2105263
# 3 1 4 8 0.6153846
# 4 1 5 5 0.3846154
From the dplyr vignette:
When you group by multiple variables, each summary peels off one level of the grouping. That makes ...
Javascript How to define multiple variables on a single line?
... |
edited Nov 12 '10 at 16:39
answered Nov 12 '10 at 16:27
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How do I set the rounded corner radius of a color drawable using xml?
... a white background, black border and rounded corners:
<?xml version="1.0" encoding="UTF-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android">
<solid android:color="#ffffffff"/>
<stroke android:width="3dp"
android:color="...
How to use shared memory with Linux in C
...lains their purpose.
return mmap(NULL, size, protection, visibility, -1, 0);
}
The following is an example program that uses the function defined above to allocate a buffer. The parent process will write a message, fork, and then wait for its child to modify the buffer. Both processes can read a...
Better way to check variable for null or empty string?
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10 Answers
10
Active
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How to calculate a logistic sigmoid function in Python?
... math.exp(-x))
And now you can test it by calling:
>>> sigmoid(0.458)
0.61253961344091512
Update: Note that the above was mainly intended as a straight one-to-one translation of the given expression into Python code. It is not tested or known to be a numerically sound implementation. I...
How accurately should I store latitude and longitude?
...tor
decimal degrees distance
places
-------------------------------
0 1.0 111 km
1 0.1 11.1 km
2 0.01 1.11 km
3 0.001 111 m
4 0.0001 11.1 m
5 0.00001 1.11 m
6 0.000001 0.111 m
7 0.0000001 1.11 cm
8 ...
Ruby: Merging variables in to a string
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answered Feb 16 '09 at 21:42
Mike WoodhouseMike Woodhouse
47.6k1212 gold badges8585 silver badges123123 bronze badges
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