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...体实现，因此很多负载平衡服务器都允许用户添加自定义脚本以执行特定于服务实例的查询。这些状态查询请求常常包含了很多测试，甚至会尝试从服务实例中返回数据。
一旦负载平衡服务器发现其所管理的某个服务实例不再...
psycopg2: insert multiple rows with one query
...ues (
cursor, insert_query, data, template=None, page_size=100
)
The pythonic way of doing it in Psycopg 2.6:
data = [(1,'x'), (2,'y')]
records_list_template = ','.join(['%s'] * len(data))
insert_query = 'insert into t (a, b) values {}'.format(records_list_template)
cursor.execute(insert_quer...
Two way/reverse map [duplicate]
I'm doing this switchboard thing in python where I need to keep track of who's talking to whom, so if Alice --> Bob, then that implies that Bob --> Alice.
...
Why do people say that Ruby is slow? [closed]
...s, but the language is very important too. Dynamic languages like Ruby and Python are slower than static typed languages simply because they require lots of type checking at runtime. Monkey patching is cool, but it is expensive.
– Wilson Freitas
Sep 11 at 19:09...
Determine if 2 lists have the same elements, regardless of order? [duplicate]
...are unique) as well as hashable (which strings and other certain immutable python objects are), the most direct and computationally efficient answer uses Python's builtin sets, (which are semantically like mathematical sets you may have learned about in school).
set(x) == set(y) # prefer this if e...
Python Matplotlib Y-Axis ticks on Right Side of Plot
...new-post-login', 'https%3a%2f%2fstackoverflow.com%2fquestions%2f10354397%2fpython-matplotlib-y-axis-ticks-on-right-side-of-plot%23new-answer', 'question_page');
}
);
Post as a guest
...
Principal component analysis in Python
...
Months later, here's a small class PCA, and a picture:
#!/usr/bin/env python
""" a small class for Principal Component Analysis
Usage:
p = PCA( A, fraction=0.90 )
In:
A: an array of e.g. 1000 observations x 20 variables, 1000 rows x 20 columns
fraction: use principal components that...
How does collections.defaultdict work?
I've read the examples in python docs, but still can't figure out what this method means. Can somebody help? Here are two examples from the python docs
...
How to deep copy a list?
...ist.
deepcopy(x, memo=None, _nil=[])
Deep copy operation on arbitrary Python objects.
See the following snippet -
>>> a = [[1, 2, 3], [4, 5, 6]]
>>> b = list(a)
>>> a
[[1, 2, 3], [4, 5, 6]]
>>> b
[[1, 2, 3], [4, 5, 6]]
>>> a[0][1] = 10
>>&g...
Iterate a list with indexes in Python
...
python enumerate function will be satisfied your requirements
result = list(enumerate([1,3,7,12]))
print result
output
[(0, 1), (1, 3), (2, 7),(3,12)]
...