大约有 8,800 项符合查询结果（耗时：0.0284秒） [XML]
unable to install pg gem
...
64
gem install pg -- --with-pg-config=/usr/pgsql-9.1/bin/pg_config
...
Pandas DataFrame Groupby two columns and get counts
...
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 ...
TCP 的那些事儿（下） - 更多技术 - 清泛网 - 专注C/C++及内核技术
...控制算法
这个算法1994年被提出，它主要对TCP Reno 做了些修改。这个算法通过对RTT的非常重的监控来计算一个基准RTT。然后通过这个基准RTT来估计当前的网络实际带宽，如果实际带宽比我们的期望的带宽要小或是要多的活，那么...
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?
...
TomTom
16.3k1313 gold badges6464 silver badges7474 bronze badges
3
...
USB Debugging option greyed out
...ebug when linked to the computer. Check it.
– DSlomer64
Jul 22 '16 at 12:25
|
show 7 more comments
...
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)
share
|
...
Conversion from Long to Double in Java
... Naman
68.5k2121 gold badges156156 silver badges264264 bronze badges
answered Sep 16 '10 at 8:23
YoKYoK
13.4k44 gold badges4444...