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How to use filter, map, and reduce in Python 3
... longer return lists:
[...]
map() and filter() return iterators. If you really need a list, a quick fix is e.g. list(map(...)), but a better fix is often to use a list comprehension (especially when the original code uses lambda), or rewriting the code so it doesn’t need a list at all. Particular...
How to deal with SettingWithCopyWarning in Pandas?
...
The SettingWithCopyWarning was created to flag potentially confusing "chained" assignments, such as the following, which does not always work as expected, particularly when the first selection returns a copy. [see GH5390 and GH5597 for background discussion.]
df[df['A'] > 2...
What is the documents directory (NSDocumentDirectory)?
...ath = paths.firstObject;
return basePath;
}
This Documents directory allows you to store files and subdirectories your app creates or may need.
To access files in the Library directory of your apps sandbox use (in place of paths above):
[NSSearchPathForDirectoriesInDomains(NSLibraryDirectory...
Rename all files in directory from $filename_h to $filename_half?
...
Just use bash, no need to call external commands.
for file in *_h.png
do
mv "$file" "${file/_h.png/_half.png}"
done
Do not add #!/bin/sh
For those that need that one-liner:
for file in *.png; do mv "$file" "${file/_h.png/_half.png}"; done
...
How to assign colors to categorical variables in ggplot2 that have stable mapping?
...maintain consistent color schemes across multiple data frames that are not all obtained by subsetting a single large data frame. Managing the factors levels in multiple data frames can become tedious if they are being pulled from separate files and not all factor levels appear in each file.
One way...
Reverse colormap in matplotlib
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The standard colormaps also all have reversed versions. They have the same names with _r tacked on to the end. (Documentation here.)
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String concatenation vs. string substitution in Python
...catenation is (significantly) faster according to my machine. But stylistically, I'm willing to pay the price of substitution if performance is not critical. Well, and if I need formatting, there's no need to even ask the question... there's no option but to use interpolation/templating.
>>&g...
Is there a simple, elegant way to define singletons? [duplicate]
...
I don't really see the need, as a module with functions (and not a class) would serve well as a singleton. All its variables would be bound to the module, which could not be instantiated repeatedly anyway.
If you do wish to use a cla...
sqlalchemy: how to join several tables by one query?
...rmissions.document,
).filter(
User.email == 'someemail',
).all()
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Fastest way to list all primes below N
...4.0 |
| sundaram3 | 416.0 |
+---------------------+-------+
Of all the methods tested, allowing numpy, for n=1000000,
primesfrom2to was the fastest tested.
+---------------------+-------+
| Method | ms |
+---------------------+-------+
| primesfrom2to | 15.9 |
| p...