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unable to install pg gem
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64
gem install pg -- --with-pg-config=/usr/pgsql-9.1/bin/pg_config
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Pandas DataFrame Groupby two columns and get counts
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C 1
4 B 1
5 B 2
6 B 1
dtype: int64
To get the same answer as waitingkuo (the "second question"), but slightly cleaner, is to groupby the level:
In [12]: df.groupby(['col5', 'col2']).size().groupby(level=1).max()
Out[12]:
col2
A 3
B 2
C ...
Performance differences between debug and release builds
...Release build version of your program. It does happen however. Both the x64 and the x86 jitters have had problems with structs. The x86 jitter has trouble with floating point consistency, producing subtly different results when the intermediates of a floating point calculation are kept in a FPU r...
Is System.nanoTime() completely useless?
...nt across all processors/cores? (Does arch matter? e.g. ppc, arm, x86, amd64, sparc).
It should or it's considered buggy.
However, on x86/x86_64, it is possible to see unsynced or variable freq TSCs cause time inconsistencies. 2.4 kernels really had no protection against this, and earl...
user authentication libraries for node.js?
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TomTom
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3
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USB Debugging option greyed out
...ebug when linked to the computer. Check it.
– DSlomer64
Jul 22 '16 at 12:25
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Round a Floating Point Number Down to the Nearest Integer?
...s because 1.9999999999999999 is actually equal to 2.0 in the internal float64 representation. I. e. it's already rounded as soon as it is parsed into a float, as a 64 bit float cannot represent that many significant digits. You can verify that with evaluating 1.9999999999999999 == 2.0. And if you su...
How to convert an int value to string in Go?
...teresting to note that strconv.Itoa is shorthand for
func FormatInt(i int64, base int) string
with base 10
For Example:
strconv.Itoa(123)
is equivalent to
strconv.FormatInt(int64(123), 10)
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Conversion from Long to Double in Java
... Naman
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answered Sep 16 '10 at 8:23
YoKYoK
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Java SE 6 vs. JRE 1.6 vs. JDK 1.6 - What do these mean?
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Jonathan LefflerJonathan Leffler
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