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MIN/MAX vs ORDER BY and LIMIT
...ay' and 'NULL' rows) whereas the SORT and LIMIT still needs needs to do an ordered traversal of the index (106,000 rows). The actual performance impact is probably negligible.
It looks like MIN() is the way to go - it's faster in the worst case, indistinguishable in the best case, is standard SQL ...
Why does the C++ STL not provide any “tree” containers?
...antees log(n) insertion/deletion/lookup (and containing elements in sorted order). This is all map is used for and is implemented (usually) as a red/black tree. A red/black tree makes sure that the tree is balanced. So the depth of the tree is directly related to the number of elements in the tree.
...
Python string class like StringBuilder in C#?
...
There is no one-to-one correlation. For a really good article please see Efficient String Concatenation in Python:
Building long strings in the Python
progamming language can sometimes
result in very slow running code. In
this article I investigate the
comp...
C++ preprocessor __VA_ARGS__ number of arguments
...
This is actually compiler dependent, and not supported by any standard.
Here however you have a macro implementation that does the count:
#define PP_NARG(...) \
PP_NARG_(__VA_ARGS__,PP_RSEQ_N())
#define PP_NARG_(...) \
...
Timeout a command in bash without unnecessary delay
...y, Bash does not support floating point arithmetic (sleep does),
therefore all delay/time values must be integers.
EOF
}
# Options.
while getopts ":t:i:d:" option; do
case "$option" in
t) timeout=$OPTARG ;;
i) interval=$OPTARG ;;
d) delay=$OPTARG ;;
*) printUsage...
How does Trello access the user's clipboard?
...source code Trello uses to accomplish the clipboard trick.
We don't actually "access the user's clipboard", instead we help the user out a bit by selecting something useful when they press Ctrl+C.
Sounds like you've figured it out; we take advantage of the fact that when you want to hit Ctrl+C, ...
jQuery: How can i create a simple overlay?
How can I create a really basic overlay in jQuery without UI?
7 Answers
7
...
When I catch an exception, how do I get the type, file, and line number?
...Error:
print(traceback.format_exc())
Output
Traceback (most recent call last):
File "/path/to/file.py", line 51, in <module>
print(4/0)
ZeroDivisionError: division by zero
Process finished with exit code 0
...
How to change the order of DataFrame columns?
... + cols[:-1]
In [13]: cols
Out[13]: ['mean', 0L, 1L, 2L, 3L, 4L]
Then reorder the dataframe like this:
In [16]: df = df[cols] # OR df = df.ix[:, cols]
In [17]: df
Out[17]:
mean 0 1 2 3 4
0 0.445543 0.445598 0.173835 0.343415 0.682252 ...
TLSF源码及算法介绍 - 开源 & Github - 清泛网 - 专注C/C++及内核技术
...及时。英文好的同学请直接看论文《TLSF: a New Dynamic Memory Allocator f 官网地址：http://www.gii.upv.es/tlsf/
官网的代码应该是主分支，github上的几个仓库更新不是那么及时。
英文好的同学请直接看论文《TLSF: a New Dynamic Memory Allocator fo...