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Automatically creating directories with file output [duplicate]
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The os.makedirs function does this. Try the following:
import os
import errno
filename = "/foo/bar/baz.txt"
if not os.path.exists(os.path.dirname(filename)):
try:
os.makedirs(os.path.dirname(filename))
except OS...
Checking if a string can be converted to float in Python
... ------------
print(isfloat("")) False
print(isfloat("1234567")) True
print(isfloat("NaN")) True nan is also float
print(isfloat("NaNananana BATMAN")) False
print(isfloat("123.456")) True
print(isfloat("123.E4")) ...
Dynamic SQL - EXEC(@SQL) versus EXEC SP_EXECUTESQL(@SQL)
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EXEC('SELECT * FROM FOO WHERE ID=?', 123) will replace the parameter placeholder "?" with the value 123 and then execute the query, returning a result for SELECT * FROM FOO WHERE ID=123
– Peter Wone
Jun 1 '10 at 23:27
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sed: print only matching group
...it with a 2nd grep.
# To extract \1 from /xx([0-9]+)yy/
$ echo "aa678bb xx123yy xx4yy aa42 aa9bb" | grep -Eo 'xx[0-9]+yy' | grep -Eo '[0-9]+'
123
4
# To extract \1 from /a([0-9]+)b/
$ echo "aa678bb xx123yy xx4yy aa42 aa9bb" | grep -Eo 'a[0-9]+b' | grep -Eo '[0-9]+'
678
9
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Build the full path filename in Python
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This works fine:
os.path.join(dir_name, base_filename + "." + filename_suffix)
Keep in mind that os.path.join() exists only because different operating systems use different path separator characters. It smooths over that difference so cross...
Where do I find old versions of Android NDK? [closed]
...bz2
http://dl.google.com/android/ndk/android-ndk-r9b-linux-x86_64.tar.bz2
OS X example:
http://dl.google.com/android/ndk/android-ndk-r9b-darwin-x86.tar.bz2
http://dl.google.com/android/ndk/android-ndk-r9b-darwin-x86_64.tar.bz2
Windows example:
http://dl.google.com/android/ndk/android-ndk-r9b-windo...
Non-alphanumeric list order from os.listdir()
...ve noticed that the default order of the lists has changed to something almost nonsensical. For example, if I am in a current directory containing the following subdirectories: run01, run02, ... run19, run20, and then I generate a list from the following command:
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What does the “yield” keyword do?
...one, etc. And generators return... well that's where yield comes in:
def f123():
yield 1
yield 2
yield 3
for item in f123():
print item
Instead of yield statements, if you had three return statements in f123() only the first would get executed, and the function would exit. But f1...
How to get an absolute file path in Python
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>>> import os
>>> os.path.abspath("mydir/myfile.txt")
'C:/example/cwd/mydir/myfile.txt'
Also works if it is already an absolute path:
>>> import os
>>> os.path.abspath("C:/example/cwd/mydir/myfile.txt")
'C:...
How to join components of a path when you are constructing a URL in Python
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Since, from the comments the OP posted, it seems he doesn't want to preserve "absolute URLs" in the join (which is one of the key jobs of urlparse.urljoin;-), I'd recommend avoiding that. os.path.join would also be bad, for exactly the same reason.
So, I'd...