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Checking if a string can be converted to float in Python
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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")) ...
How to find if directory exists in Python
In the os module in Python, is there a way to find if a directory exists, something like:
13 Answers
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When to use os.name, sys.platform, or platform.system?
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Dived a bit into the source code.
The output of sys.platform and os.name are determined at compile time. platform.system() determines the system type at run time.
sys.platform is specified as a compiler define during the build configuration.
os.name checks whether certain os specific mod...
How to use glob() to find files recursively?
...les in the current directory or hidden files on Unix based system, use the os.walk solution below.
os.walk
For older Python versions, use os.walk to recursively walk a directory and fnmatch.filter to match against a simple expression:
import fnmatch
import os
matches = []
for root, dirnames, filena...
How to create a zip archive of a directory in Python?
...s easiest to explain with some example code:
#!/usr/bin/env python
import os
import zipfile
def zipdir(path, ziph):
# ziph is zipfile handle
for root, dirs, files in os.walk(path):
for file in files:
ziph.write(os.path.join(root, file))
if __name__ == '__main__':
z...
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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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 find out the number of CPUs using python
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On Python 3.6.2 I could only use os.cpu_count()
– Achilles
Sep 11 '17 at 19:59
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Python: What OS am I running on?
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>>> import os
>>> os.name
'posix'
>>> import platform
>>> platform.system()
'Linux'
>>> platform.release()
'2.6.22-15-generic'
The output of platform.system() is as follows:
Linux: Linux
Mac: Darw...