Can you edit a .py script from another?

Question

I'm creating a similarity program that calculates the euclidean distance of images, I'm looking for user input so that if they want to use a portion of the code, they can choose so. in that case, a line (specifically 13 in dc2.py) needs to be changed to " ". How can i go about this?

I've attempted using the open function alongside .write, opening a file though open(dc.py).read(), and to no avail.

This converts the image into an array (program dc2.py):

import numpy as np
import imageio
from numpy import array


img = imageio.imread("Machine Screw.jpg")
data = array(img)

with open('test2.txt', 'w') as outfile:

        np.savetxt(outfile, data_slice, fmt='%-7.2f')

exec(open("Halfer.py").read())

Here's the failed code to change the previous .py:

inp = input("Want to use halfer?: ")

if inp == 'y':
    the_file = open('dc2.py', 'a')
    the_file[13].write(' ')

--------------------------------------

I expected:

Process finished with exit code 0

here's what actually happened:

Traceback (most recent call last):
  File "C:/Users/User/Desktop/PySimCode/Resources/Ini.py", line 5, in <module>
    the_file[13].write(' ')
TypeError: '_io.TextIOWrapper' object is not subscriptable

Thank you for all the help!

I think a better way to do this is passing a parameter to `dc2.py` to determine if line 13 needs to be executed. — Brian, Aug 05 '19 at 05:50
There’s usually no reason to edit files. Pass parameters, call functions with arguments etc. — Sami Kuhmonen, Aug 05 '19 at 05:50
I rarely see people editing `*.py` files when running their programs. — Brian, Aug 05 '19 at 05:50
Also don't do `exec(open("Halfer.py").read())`... There are specific ways for running files from scripts: https://stackoverflow.com/questions/7974849/how-can-i-make-one-python-file-run-another — Tomerikoo, Aug 05 '19 at 05:54
Self modifying code questions? History is already repeating itself. — , Aug 05 '19 at 06:58

milanbalazs · Answer 1 · 2019-08-05T06:19:31.433

Your solution what you want to implement is not too "Pythonic". In my opinion you should import dc2.py file as module to Ini.py script and use parameters based on user-input to manipulate the behavior of dc2.py script.

For example:

dc2.py

import numpy as np
import imageio
import subprocess
from numpy import array


def image_converter(halfer_needed=True):
    img = imageio.imread("Machine Screw.jpg")
    data = array(img)

    with open('test2.txt', 'w') as outfile:

        np.savetxt(outfile, data, fmt='%-7.2f')

    if halfer_needed:
        sp = subprocess.Popen(["python", "Halfer.py"])  # Call Halfer.py script
        ret_stdout, ret_stderr = sp.communicate()  # These variables contain the STDOUT and STDERR
        ret_retcode = sp.returncode  # This variable conains the return code of your command

I think you want to call the Halfer.py script if user wants it so I have used the subprocess module to call this script as you can see above. You can see more details and options about this module: https://docs.python.org/3/library/subprocess.html

Ini.py

from dc2 import image_converter  # Import your function from "dc2.py" script 

inp = str(input("Want to use halfer?: "))

if inp == 'y':
    image_converter(halfer_needed=False)
image_converter()  # you don't need to define the keyword argument because the default value is True.

score 1 · Answer 2 · answered Aug 05 '19 at 06:20

Try this:

inp = raw_input("Want to use halfer?: ")

if inp == 'y':
    origin_file = open('dc2.py','r').readlines()
    the_file = open('dc2.py','w')
    origin_file[12] = '\n'
    for line in origin_file:
        the_file.write(line)
    the_file.close()

Some notes I'd like to add:

input reads a block of text and parses it. You should probably always use raw_input.
open does different things, depending on the mode parameter. In my case, I used r for reading, then w for writing. (I don't think there's a way to read and write on the same <open> object). a is append, which only lets you add lines. Read here
To get the contents from an <open>, use .read() or .readlines().
The 13th line is index 12. Also, I changed it to '\n' instead of ' '.
Don't forget to call .close() on your <open> when you are done with it!

Hope this works for you!

score 0 · Accepted Answer · answered Aug 05 '19 at 06:40

You can, but you shouldn't.

You are trying to activate some code based on uer imput, this is doable encapsulating the code in functions, that you can import and axecute based on a condition. You are trying to achieve this result by reading files and executing them manually, basically you are doing what the Python interpreter should do..

First, you need to chage you modules to something that activates at will, not as soon as the file is loaded, for instance your dc2.py would look like this:

import numpy as np
import imageio
from numpy import array

import Halfer  # <- here you import the py file, not open and read

def run(use_halfer):
    img = imageio.imread("Machine Screw.jpg")
    data = array(img)

    with open('test2.txt', 'w') as outfile:
        np.savetxt(outfile, data_slice, fmt='%-7.2f')

    if use_halfer:
        Halfer.run()

..and your Halfer.py file should look like this:

def run():
    # ..all your Halfer.py code here inside the run function

..and then your starting point of the script can look like:

import dc2
inp = input("Want to use halfer?: ")

dc2.run(inp == 'y')  # <- here you tell dc2 to use halfer or not.

Can you edit a .py script from another?

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Process finished with exit code 0

3 Answers3