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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")) ...
Getting file size in Python? [duplicate]
...
Use os.path.getsize(path) which will
Return the size, in bytes, of path. Raise OSError if the file does not exist or is inaccessible.
import os
os.path.getsize('C:\\Python27\\Lib\\genericpath.py')
Or use os.stat(path).st_...
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...
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
...
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
...
Rename multiple files in a directory in Python [duplicate]
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Use os.rename(src, dst) to rename or move a file or a directory.
$ ls
cheese_cheese_type.bar cheese_cheese_type.foo
$ python
>>> import os
>>> for filename in os.listdir("."):
... if filename.startswith("chee...
How to get file creation & modification date/times in Python?
...
Getting some sort of modification date in a cross-platform way is easy - just call os.path.getmtime(path) and you'll get the Unix timestamp of when the file at path was last modified.
Getting file creation dates, on the other hand, is fiddly and platform-dependent, diff...
How to delete a file or folder?
...
os.remove() removes a file.
os.rmdir() removes an empty directory.
shutil.rmtree() deletes a directory and all its contents.
Path objects from the Python 3.4+ pathlib module also expose these instance methods:
pathlib.P...
How to get all of the immediate subdirectories in Python
...;dr:
Always use scandir:
list_subfolders_with_paths = [f.path for f in os.scandir(path) if f.is_dir()]
Bonus: With scandir you can also simply only get folder names by using f.name instead of f.path.
This (as well as all other functions below) will not use natural sorting. This means results w...
How to delete the contents of a folder?
...
import os, shutil
folder = '/path/to/folder'
for filename in os.listdir(folder):
file_path = os.path.join(folder, filename)
try:
if os.path.isfile(file_path) or os.path.islink(file_path):
os.unlink(file_p...