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What is the python “with” statement designed for?
...ort os
@contextmanager
def working_directory(path):
current_dir = os.getcwd()
os.chdir(path)
try:
yield
finally:
os.chdir(current_dir)
with working_directory("data/stuff"):
# do something within data/stuff
# here I am back again in the original working directory...
Thou shalt not inherit from std::vector
...of different types of iterators: const iterators, random access iterators, etc.
Therefore I recommend you to accept this convention and design your algorithms in such way that they won't care about what is the container they're working on - and they would only require a specific type of iterator wh...
How to write to a file, using the logging Python module?
...se a configuration file. It allows me to switch logging levels, locations, etc without changing code when I go from development to release. I simply package a different config file with the same name, and with the same defined loggers.
import logging.config
if __name__ == '__main__':
# Configur...
Group by multiple columns in dplyr, using string vector input
...t contains bunch of wrapper functions like s_group_by, s_mutate, s_filter, etc that use string arguments. You can mix them with the normal dplyr functions. For example
cols = c("cyl","gear")
mtcars %.%
s_group_by(cols) %.%
s_summarise("avdisp=mean(disp), max(disp)") %.%
arrange(avdisp)
...
Generating CSV file for Excel, how to have a newline inside a value
...re are packages/libraries available for doing that in Python/Perl/PHP/.NET/etc
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Relative paths in Python
...e on my system (python 2.5.1 on OS X 10.5.7):
#foo.py
import os
print os.getcwd()
print __file__
#in the interactive interpreter
>>> import foo
/Users/jason
foo.py
#and finally, at the shell:
~ % python foo.py
/Users/jason
foo.py
However, I do know that there are some quirks with __fil...
What rules does Pandas use to generate a view vs a copy?
...a single dtype case (which could be a 1-d for a series, a 2-d for a frame, etc). numpy may generate a view; it depends on what you are slicing; sometimes you can get a view and sometimes you can't. pandas doesn't rely on this fact at all as its not always obvious whether a view is generated. but thi...
How can I check if a URL exists via PHP?
...returned by get_headers() are well formed.
Use curl (if you can).
Prevent fetching the entire body/content, but only request the headers.
Consider redirecting urls:
Do you want the first code returned?
Or follow all redirects and return the last code?
You might end up with a 200, but it could redire...
When to use a Content Provider
...e access to a singleton instance (the ContentResolver) to perform queries, etc. Of course you could implement your own Loader to use for your SQLite database... of course you could implement access to a single database instance across the entire application... and of course a ContentProvider isn't r...
Performance of Java matrix math libraries? [closed]
... not? For some purposes, eg when one is parallelizing using mpi or hadoop etc, the important time is actually the singlecore time, since the mpi/hadoop implementation takes care of parallelizing things. (At least, for me jblas was about 2.5 faster than jama, not 10 times faster than jama as you got...