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Apply a function to every row of a matrix or a data frame
... 3 4
[3,] 5 6
R> apply(M, 1, function(x) 2*x[1]+x[2])
[1] 4 10 16
R>
This takes a matrix and applies a (silly) function to each row. You pass extra arguments to the function as fourth, fifth, ... arguments to apply().
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How can I profile C++ code running on Linux?
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1440
If your goal is to use a profiler, use one of the suggested ones.
However, if you're in a hurry...
How to avoid reinstalling packages when building Docker image for Python projects?
...ree
.
├── Dockerfile
├── requirements.txt
└── run.py
0 directories, 3 file
# Dockerfile
FROM dockerfile/python
WORKDIR /srv
ADD ./requirements.txt /srv/requirements.txt
RUN pip install -r requirements.txt
ADD . /srv
CMD python /srv/run.py
# requirements.txt
pytest==2.3.4
# ...
Context switches much slower in new linux kernels
We are looking to upgrade the OS on our servers from Ubuntu 10.04 LTS to Ubuntu 12.04 LTS. Unfortunately, it seems that the latency to run a thread that has become runnable has significantly increased from the 2.6 kernel to the 3.2 kernel. In fact the latency numbers we are getting are hard to belie...
How can I get the current network interface throughput statistics on Linux/UNIX? [closed]
...phs for the current network utilisation on specific interfaces, such as eth0. How can I return that information at the command line on Linux/UNIX?
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How to detect a Christmas Tree? [closed]
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How do I create an average from a Ruby array?
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20 Answers
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Reference — What does this symbol mean in PHP?
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20 Answers
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Find which version of package is installed with pip
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1070
As of pip 1.3, there is a pip show command.
$ pip show Jinja2
---
Name: Jinja2
Version: 2.7.3...
How do I replace NA values with zeros in an R dataframe?
...nt in @gsk3 answer. A simple example:
> m <- matrix(sample(c(NA, 1:10), 100, replace = TRUE), 10)
> d <- as.data.frame(m)
V1 V2 V3 V4 V5 V6 V7 V8 V9 V10
1 4 3 NA 3 7 6 6 10 6 5
2 9 8 9 5 10 NA 2 1 7 2
3 1 1 6 3 6 NA 1 4 1 6
4 NA 4 NA 7 10 2 NA 4 1...