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Storing time-series data, relational or non?
...n is never a Key (duplicate rows, which are prohibited in a Relational database, must be prevented by other means).
The Id column requires an additional Index, which obviously impedes the speed of INSERT/DELETE, and adds to the disk space used.
You can get rid of it. Please.
Elevation
Now ...
How do I get the row count of a pandas DataFrame?
...eturn non-NaN counts for each column:
df.count()
A 5
B 3
dtype: int64
For Series, use Series.count to similar effect:
s.count()
# 3
Group-wise Row Count: GroupBy.size
For DataFrames, use DataFrameGroupBy.size to count the number of rows per group.
df.groupby('A').size()
A
a 2
b ...
Why does using an Underscore character in a LIKE filter give me all the results?
...ess supports like operator. My solution will work in most, if not all, databases.
– Rachcha
Oct 25 '13 at 13:51
2
...
How to allow only numeric (0-9) in HTML inputbox using jQuery?
...lue); // Allow digits only, using a RegExp
});
});
See the JSFiddle demo for more input filter examples. Also note that you still must do server side validation!
Pure JavaScript (without jQuery)
jQuery isn't actually needed for this, you can do the same thing with pure JavaScript as well. S...
Benchmarking (python vs. c++ using BLAS) and (numpy)
...
CPU: 2 x 16 Intel(R) Xeon(R) E2560 Sandy Bridge @ 2.00GHz (16 Cores)
RAM: 64 GB
Ivy (MKL, OpenBLAS, ATLAS):
CPU: 2 x 20 Intel(R) Xeon(R) E2680 V2 Ivy Bridge @ 2.80GHz (20 Cores, with HT = 40 Cores)
RAM: 256 GB
Software
The software stack is for both nodes the sam. Instead of GotoBLAS2, OpenB...
Can you use CSS to mirror/flip text?
... that when the standard is adopted by a browser, it will use the standards-based version instead of the (older, buggier) prefixed version. In this case, that means "transform: matrix(-1, 0, 0, 1, 0, 0);" should be the last property. (Edited the answer to reflect this.)
– Jay Da...
AtomicInteger lazySet vs. set
...ite. There are a few
other use cases along these lines for non-reference-based
atomics as well, so the method is supported across all of the
AtomicX classes.
For people who like to think of these operations in terms of
machine-level barriers on common multiprocessors, lazySet
provides...
Node.js + Nginx - What now?
...d I want Node applications to be mounted to subfolders (i.e. http://myhost/demo/pet-project/) without introducing any configuration dependency to the application code.
At the same time I want other stuff like blog to run on the same web server.
Sounds simple huh? Apparently not.
In ma...
“Code too large” compilation error in Java
...
A single method in a Java class may be at most 64KB of bytecode.
But you should clean this up!
Use .properties file to store this data, and load it via java.util.Properties
You can do this by placing the .properties file on your classpath, and use:
Properties propert...
What is the difference between char array and char pointer in C?
...
gsamaras
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answered Apr 17 '12 at 7:15
JonJon
...