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postgresql - sql - count of `true` values
...select count(*) filter (where myCol)
from tbl;
The above query is a bad example in that a simple WHERE clause would suffice, and is for demonstrating the syntax only. Where the FILTER clause shines is that it is easy to combine with other aggregates:
select count(*), -- all
count(myCol), ...
How can I pass arguments to a batch file?
...
Another useful tip is to use %* to mean "all". For example:
echo off
set arg1=%1
set arg2=%2
shift
shift
fake-command /u %arg1% /p %arg2% %*
When you run:
test-command admin password foo bar
the above batch file will run:
fake-command /u admin /p password admin password...
No line-break after a hyphen
...
You could also wrap the relevant text with
<span style="white-space: nowrap;"></span>
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Why is unsigned integer overflow defined behavior but signed integer overflow isn't?
...ed integer overflow is well defined by both the C and C++ standards. For example, the C99 standard ( §6.2.5/9 ) states
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How to merge lists into a list of tuples?
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@Adrien: cheers for your applicable comment. For Python 2.x, s/zip_longest()/izip_longest(). Renamed in Python 3.x to zip_longest().
– mechanical_meat
Jul 10 '11 at 19:13
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What is the correct way to document a **kwargs parameter?
I'm using sphinx and the autodoc plugin to generate API documentation for my Python modules. Whilst I can see how to nicely document specific parameters, I cannot find an example of how to document a **kwargs parameter.
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postgresql port confusion 5433 or 5432?
I have installed postgresql on OSX. When I run psql, I get
7 Answers
7
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Python: fastest way to create a list of n lists
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The probably only way which is marginally faster than
d = [[] for x in xrange(n)]
is
from itertools import repeat
d = [[] for i in repeat(None, n)]
It does not have to create a new int object in every iteration and is about 15 % faster on my machine.
Edit: Using NumPy, you can avoid t...
Which is more efficient, a for-each loop, or an iterator?
... there is no difference between using an iterator or the new for loop syntax, as the new syntax just uses the iterator underwater.
If however, you mean by loop the old "c-style" loop:
for(int i=0; i<list.size(); i++) {
Object o = list.get(i);
}
Then the new for loop, or iterator, can be a ...
Heatmap in matplotlib with pcolor?
..."http://datasets.flowingdata.com/ppg2008.csv")
nba = pd.read_csv(page, index_col=0)
# Normalize data columns
nba_norm = (nba - nba.mean()) / (nba.max() - nba.min())
# Sort data according to Points, lowest to highest
# This was just a design choice made by Yau
# inplace=False (default) ->thanks ...