getRandomImages.py

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Program      : GetRandomImages.py
Description  : This program requests an image from a url and saves it locally. 
               Additionally, it renames the image name in order to prevent
               images being overwritten.
               

Author       : Burak Can Ozter - B00784243 , burak.ozter@dal.ca
Date         : April 3rd, 2019

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''' Libraries '''
import urllib.request
import os
import re


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*Function Name : save_as()
*Arguments     : string file_name
*Return Value  : string
*Description   : This function checks if the specified file name already exists 
                 and if it does, it increments the file number and saves it in 
                 the current folder.
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def save_as(file_name):
    ''' File exists '''
    if(os.path.exists(file_name)):
        print("File already exists...")
        print("Renaming file...")

        ''' Repeat until the file name is unique so it does not overwrite '''
        while(os.path.exists(file_name)):
            ''' File name does not have a number '''
            if not (re.search(r'\d+', file_name)):
                ''' Assign a number '''
                new_file_name = file_name.split(".")[0] + "0.png"
                file_name = new_file_name
                new_file_name = re.search(r'\d+', file_name).group()
            else:
                ''' File name already has a number '''
                new_file_name = re.search(r'\d+', file_name).group()


            ''' Increment file name number.
                For instance, xxx9 -> xxx10 
            '''
            file_name = file_name.replace(new_file_name,str(int(new_file_name) + 1))

            ''' Check if it is a unique name '''
            if not(os.path.exists(file_name)):
                print("New file has been saved as ", file_name)
                return file_name
    else:
        ''' Valid file name'''
        print("New image file created as ", file_name)
        return file_name



''' Request images from a url '''

urllib.request.urlretrieve("https://picsum.photos/256/256/?random", save_as("pub.png") )

urllib.request.urlretrieve("https://picsum.photos/256/256/?random", save_as("pk.png") )