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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")) ...
os.walk without digging into directories below
How do I limit os.walk to only return files in the directory I provide it?
20 Answers
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`from … import` vs `import .` [duplicate]
...urself when you import for simplicity or to avoid masking built ins:
from os import open as open_
# lets you use os.open without destroying the
# built in open() which returns file handles.
share
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How to check if a file exists in Go?
... function solely intended to check if a file exists or not (like Python's os.path.exists ). What is the idiomatic way to do it?
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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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How can I safely create a nested directory?
What is the most elegant way to check if the directory a file is going to be written to exists, and if not, create the directory using Python? Here is what I tried:
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How to find the operating system version using JavaScript?
How can I find the OS name and OS version using JavaScript?
13 Answers
13
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How to access environment variable values?
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Environment variables are accessed through os.environ
import os
print(os.environ['HOME'])
Or you can see a list of all the environment variables using:
os.environ
As sometimes you might need to see a complete list!
# using get will return `None` if a key is not...
Python list directory, subdirectory, and files
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Use os.path.join to concatenate the directory and file name:
for path, subdirs, files in os.walk(root):
for name in files:
print os.path.join(path, name)
Note the usage of path and not root in the concatenation, sinc...