How to create a list of open image command from an image list-CodePudding

I need to create a list of open image commands from an image list. I have to do it like that, instead of doing the "open image" inside a for because I need to pass to a function the data in this exact format.

Let me explain better.

This is the format that I have:

img_my_list=['img_1.png','img_2.png', 'img_3.png']

This is the format that i need for my function (I cannot use a for inside my function):

img_open_format_list = [(open(join(dirname(__file__), 'img_1.png'), 'rb'), 'image/png'),
        (open(join(dirname(__file__), 'img_2.png'), 'rb'), 'image/png'),
        (open(join(dirname(__file__), 'img_3.png'), 'rb'), 'image/png')]

How can I transform the list?

CodePudding user response：

Every open should be accompanied by a close unless used as a context manager.

The contextlib.ExitStack is perfectly suited for that task.

from contextlib import ExitStack

img_my_list=['img_1.png','img_2.png', 'img_3.png']

with ExitStack() as stack:
    images = [(stack.enter_context(open(img, 'rb')), 'image/png') for img in img_my_list]
    ...  # do work

As you exit the scope, all opened images will be closed.

CodePudding user response：

I figure it out that it can be done with map:

img_my_list = ['img_1.png','img_2.png', 'img_3.png']

img_open_command_list = map(lambda x: (open(x, 'rb'), 'image/png'), img_my_list)

This way I get the open command list that I desire by doing: list(img_open_command_list). And the images are attached perfectly in my report.