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When and why are database joins expensive?
...r special cases
It all comes back to mitigating the size of the working set. Joins involving properly selected keys with correctly set up indexes are cheap, not expensive, because they allow significant pruning of the result before the rows are materialised.
Materialising the result involves bu...
Conditional Replace Pandas
...hich df.my_channel > 20000 is True, while df.loc[mask, column_name] = 0 sets the value 0 to the selected rows where maskholds in the column which name is column_name.
Update:
In this case, you should use loc because if you use iloc, you will get a NotImplementedError telling you that iLocation b...
O(nlogn) Algorithm - Find three evenly spaced ones within binary string
... significantly better. As in sdcvvc's answer, we can take the "Cantor-like set" of strings of length n=3k, with 1s at the positions whose ternary representation has only 0s and 2s (no 1s) in it. Such a string has 2k = n(log 2)/(log 3) ≈ n0.63 ones in it and no evenly spaced 1s, so checking all pai...
Matplotlib discrete colorbar
...n my method) is making 0 showup as grey.
For images i often use the cmap.set_bad() and convert my data to a numpy masked array. That would be much easier to make 0 grey, but i couldnt get this to work with the scatter or the custom cmap.
As an alternative you can make your own cmap from scratch,...
Android Google Maps v2 - set zoom level for myLocation
Is it possible to change the zoom level for myLocation with the new Google Maps API v2?
13 Answers
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How to get a reference to current module's attributes in Python
... However, it doesn't seem to work from ipdb (insert "import ipdb; ipdb.set_trace()" into your file).
– gatoatigrado
Jun 20 '12 at 22:04
9
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Rename multiple files based on pattern in Unix
There are multiple files in a directory that begin with prefix fgh , for example:
22 Answers
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How do I make UILabel display outlined text?
... drawTextInRect:
- (void)drawTextInRect:(CGRect)rect {
CGSize shadowOffset = self.shadowOffset;
UIColor *textColor = self.textColor;
CGContextRef c = UIGraphicsGetCurrentContext();
CGContextSetLineWidth(c, 1);
CGContextSetLineJoin(c, kCGLineJoinRound);
CGContextSetTextDrawingMode(c, ...
JSTL in JSF2 Facelets… makes sense?
...lasses with additional properties in Mojarra versions before 2.2.7.
<c:set> vs <ui:param>
They are not interchangeable. The <c:set> sets a variable in the EL scope, which is accessible only after the tag location during view build time, but anywhere in the view during view render...
Obtaining a powerset of a set in Java
The powerset of {1, 2, 3} is:
26 Answers
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