Saving tuple with numbers to file as string

Question

I'm starting with Python in Machine Learning, I'm interested in solving old Kaggle competition for my own. First thing I need to do is to convert list of encoded pixels to a bounding box, convert it to have top left and bottom right rectangle coordinates, have it in specific output and save it to a file

I found already examples where using RLE algorithm convert encoded pixels and I need to change it to save to the file. My particular problem is saving a tuple to a file in x1,y1,x2,y2 format

I have a code, which takes the first and the last coordinate from the list of pixels. First I tried with:

f = open("file.txt", "w")
f.write(str(mask_pixels[0]) + str(mask_pixels[len(mask_pixels)-1]))
f.write("\n")
f.close()

But the output is like (469, 344)(498, 447) (which is a tuple, so that's fine).

I tried to use join function as following:

coordinates = mask_pixels[0], mask_pixels[len(mask_pixels)-1]
f = open("file.txt", "w")
for x in coordinates:
    f.write(",".join(str(x)))
f.write("\n")
f.close()

But it saves it as (,4,6,9,,, ,3,4,4,)(,4,9,8,,, ,4,4,7,)

So I tried with

f = open("file.txt", "a")
f.write(str(coordinate1))
f.write(",")
f.write(str(coordinate2))
f.write("\n")
f.close()

But it saves it as (469, 344),(498, 447) , which is still something I'm not looking for. Can anyone show me a hint how should I do it to have in a file something like 469,344,498,447 ? I'm not asking for a code directly (I know you guys might not have time for it), but I'm looking for an idea what should I read/learn.

Answer 1

with open("file.txt", "w") as f:
    print(*sum((mask_pixels[0],mask_pixels[-1]),()),sep=', ',file=f)

Output

469, 344, 498, 447

Answer 2

You can transform your tuples in list and concatenate them :

a = (469, 344)
b= (498,447)
result = list(a) + list(b)

Output :

[469, 344, 498, 447]

To go back to your code it could look something like that :

f = open("file.txt", "w")
f.write(str(list(str(mask_pixels[0])) + list(str(mask_pixels[len(mask_pixels)-1]))))
f.write("\n")
f.close()

---

And if you want to save all of your mask you could even do a double list comprehension :

a = (469, 344)
b= (498,447)
c = (512,495)
list_of_tuples = [a, b, c]
result = [item for sublist in list_of_tuples for item in sublist]

Out : [469, 344, 498, 447, 512, 495]