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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...
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...
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.
...
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
...
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)]
...
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...
Python base64 data decode
I have the following piece of base64 encoded data, and I want to use python base64 module to extract information from it. It seems that module does not work. Can anyone tell me how?
...