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Iterate a directory for all files with file extension '.py'

I am attempting to find every file in a directory that contains the file extension: '.py'
I tried doing:
if str(file.contains('.py')):
pass
I also thought of doing a for loop and going through each character in the filename but thought better of it, thinking that it would be too intense, and concluded that there would be an easier way to do things.
Below is an example of what I would want my code to look like, obviously replacing line 4 with an appropriate answer.
def find_py_in_dir():
for file in os.listdir():
#This next line is me guessing at some method
if str(file.contains('.py')):
pass

Ideally, you'd use endswith('.py') for actual file extensions, not checking substrings (which you'd do using in statements)
But, forget the if statement
https://docs.python.org/3/library/glob.html
import glob
for pyile in glob.glob('*.py'):
print(pyile)

if requires a boolean and not a string, so remove the str and replace .contains with .__contains__
if file.__contains__ ('.py'):
You can also do:
if '.py' in file:

How to pull a substring off a string without knowing what the string is (file path)

I have a given file path. For example, "C:\Users\cobyk\Downloads\GrassyPath.jpg". I would like to pull in a separate string, the image file name.
I'm assuming the best way to do that is to start from the back end of the string, find the final slash and then take the characters following that slash. Is there a method to do this already or will I have search through the string via a for loop, find the last slash myself, and then do the transferring manually?

The pathlib module makes it very easy to access individual parts of a file path like the final path component:
from pathlib import Path
image_path = Path(r"C:\Users\cobyk\Downloads\GrassyPath.jpg")
print(image_path.name) # -> GrassyPath.jpg

You can certainly search manually as you've suggested. However, the Python standard library already has, as you suspected, a function which does this for you.
import os
file_name = os.path.basename(r'C:\Users\cobyk\Downloads\GrassyPath.jpg')

Python string alphabet removal?

So in my program, I am reading in files and processing them.
My output should say just the file name and then display some data
When I am looping through files and printing output by their name and data,
it displays for example: myfile.txt. I don't want the .txt part. just myfile.
how can I remove the .txt from the end of this string?

The best way to do it is in the example
import os
filename = 'myfile.txt'
print(filename)
print(os.path.splitext(filename))
print(os.path.splitext(filename)[0])
More info about this very useful builtin module
https://docs.python.org/3.8/library/os.path.html

The answers given are totally right, but if you have other possible extensions, or don't want to import anything, try this:
name = file_name.rsplit(".", 1)[0]

You can use pathlib.Path which has a stem attribute that returns the filename without the suffix.
>>> from pathlib import Path
>>> Path('myfile.txt').stem
'myfile'

Well if you only have .txt files you can do this
file_name = "myfile.txt"
file_name.replace('.txt', '')
This uses the built in replace functionality. You can find more info on it here!

Python Convert Windows File path in a variable

Given is a variable that contains a windows file path. I have to then go and read this file. The problem here is that the path contains escape characters, and I can't seem to get rid of it. I checked os.path and pathlib, but all expect the correct text formatting already, which I can't seem to construct.
For example this. Please note that fPath is given, so I cant prefix it with r for a rawpath.
#this is given, I cant rawpath it with r
fPath = "P:\python\t\temp.txt"
file = open(fPath, "r")
for line in file:
print (line)
How can I turn fPath via some function or method from:
"P:\python\t\temp.txt"
to
"P:/python/t/temp.txt"
I've tried also tried .replace("\","/"), which doesnt work.
I'm using Python 3.7 for this.

You can use os.path.abspath() to convert it:
print(os.path.abspath("P:\python\t\temp.txt"))
>>> P:/python/t/temp.txt
See the documentation of os.path here.

I've solved it.
The issues lies with the python interpreter. \t and all the others don't exist as such data, but are interpretations of nonprint characters.
So I got a bit lucky and someone else already faced the same problem and solved it with a hard brute-force method:
http://code.activestate.com/recipes/65211/
I just had to find it.
After that I have a raw string without escaped characters, and just need to run the simple replace() on it to get a workable path.

You can use Path function from pathlib library.
from pathlib import Path
docs_folder = Path("some_folder/some_folder/")
text_file = docs_folder / "some_file.txt"
f = open(text_file)

if you would like to do replace then do
replace("\\","/")

When using python version >= 3.4, the class Path from module pathlib offers a function called as_posix, which will sort of convert a path to *nix style path. For example, if you were to build Path object via p = pathlib.Path('C:\\Windows\\SysWOW64\\regedit.exe'), asking it for p.as_posix() it would yield C:/Windows/SysWOW64/regedit.exe. So to obtain a complete *nix style path, you'd need to convert the drive letter manually.

I came across similar problem with Windows file paths. This is what is working for me:
import os
file = input(str().split('\\')
file = '/'.join(file)
This gave me the input from this:
"D:\test.txt"
to this:
"D:/test.txt"
Basically when trying to work with the Windows path, python tends to replace '' to '\'. It goes for every backslash. When working with filepaths, you won't have double slashes since those are splitting folder names.
This way you can list all folders by order by splitting '\' and then rejoining them by .join function with frontslash.
Hopefully this helps!

Extracting penultimate folder name from path

Does anyone know a clever way to extract the penultimate folder name from a given path?
eg folderA/folderB/folderC/folderD
-> I want to know what the name of folderC is, I don't know the names of the other folders and there may be a variable number of directories before folderC but it's always the 2nd to last folder.
everything i come up with seems too cumbersome (eg getting name of folderD using basename and normpath, removing this from path string, and the getting folderC
cheers, -m

There isn't a good way to skip directly to portions within a path in a single call, but what you want can be easily done like so:
>>> os.path.basename(os.path.dirname('test/splitting/folders'))
'splitting'
Alternatively, if you know you'll always be on a filesystem with '/' delineated paths, you can just use regular old split() to get there directly:
>>> 'test/splitting/folders'.split('/')[-2]
'splitting'
Although this is a bit more fragile. The dirname+basename combo works with/without a file at the end of the path, where as the split version you have to alter the index

yep, there sure is:
>>> import os.path
>>> os.path.basename(os.path.dirname("folderA/folderB/folderC/folderD"))
'folderC'
That is, we find the 'parent directory' of the named path, and then extract the filename of the resulting path from that.