Passing values and calling functions from other functions

Question

I have this class that consists of 3 functions. Each function is in charge of one part of the whole process.

.load() loads up two files, re-formats their content and writes them to two new files.

.compare() takes two files and prints out their differences in a specific format.

.final() takes the result of .compare() and creates a file for every set of values.

Please ignore the Frankenstein nature of the logic as it is not my main concern at the moment. I know it can be written a thousand times better and that's fine by me for now as i am still new to Python and programing in general. I do have some theoretical experience but very limited technical practice and that is something i am working on.

Here is the code:

from collections import defaultdict
from operator import itemgetter
from itertools import groupby
from collections import deque
import os


class avs_auto:


    def load(self, fileIn1, fileIn2, fileOut1, fileOut2):
        with open(fileIn1+'.txt') as fin1, open(fileIn2+'.txt') as fin2:
            frame_rects = defaultdict(list)
            for row in (map(str, line.split()) for line in fin1):
                id, frame, rect = row[0], row[2], [row[3],row[4],row[5],row[6]]
                frame_rects[frame].append(id)
                frame_rects[frame].append(rect)
            for row in (map(str, line.split()) for line in fin2):
                id, frame, rect = row[0], row[2], [row[3],row[4],row[5],row[6]]
                frame_rects[frame].append(id)
                frame_rects[frame].append(rect)

        with open(fileOut1+'.txt', 'w') as fout1, open(fileOut2+'.txt', 'w') as fout2:
            for frame, rects in sorted(frame_rects.iteritems()):
                fout1.write('{{{}:{}}}\n'.format(frame, rects))
                fout2.write('{{{}:{}}}\n'.format(frame, rects))

    def compare(self, f1, f2):
        with open(f1+'.txt', 'r') as fin1:
            with open(f2+'.txt', 'r') as fin2:
                lines1 = fin1.readlines()
                lines2 = fin2.readlines()
                diff_lines = [l.strip() for l in lines1 if l not in lines2]
                diffs = defaultdict(list)
                with open(f1+'x'+f2+'Result.txt', 'w') as fout:
                    for line in diff_lines:
                        d = eval(line)
                        for k in d:
                            list_ids = d[k]
                            for i in range(0, len(d[k]), 2):
                                diffs[d[k][i]].append(k)
                    for id_ in diffs:
                        diffs[id_].sort()
                        for k, g in groupby(enumerate(diffs[id_]), lambda (i, x): i - x):
                            group = map(itemgetter(1), g)
                            fout.write('{0} {1} {2}\n'.format(id_, group[0], group[-1]))

    def final(self):
        with open('hw1load3xhw1load2Result.txt', 'r') as fin:
            lines = (line.split() for line in fin)
            for k, g in groupby(lines, itemgetter(0)):
                fst = next(g)
                lst = next(iter(deque(g, 1)), fst)
                with open('final/{}.avs'.format(k), 'w') as fout:
                    fout.write('video0=ImageSource("MovieName\original\%06d.jpeg", {}, {}, 15)\n'.format(fst[1], lst[2]))

Now to my question, how do i make it so each of the functions passes it's output files as values to the next function and calls it?

So for an example:

running .load() should output two files, call the .compare() function passing it those two files.

Then when .compare() is done, it should pass .final() the output file and calls it.

So .final() will open whatever file is passed to it from .compare() and not "test123.txt" as it is defined above.

I hope this all makes sense. Let me know if you need clarification. Any criticism is welcome concerning the code itself. Thanks in advance.

Answer 1

There are a couple of ways to do this, but I would write a master function that calls the other three in sequence. Something like:

def load_and_compare(self, input_file1, input_file2, output_file1, output_file2, result_file):
    self.load(input_file1, input_file2, output_file1, output_file2)
    self.compare(output_file1, output_file2)
    self.final(result_file)

Looking over your code, I think you have a problem in load. You only declare a single dictionary, then load the contents of both files into it and write those same contents out to two files. Because each file has the same content, compare won't do anything meaningful.

Also, do you really want to write out the file contents and then re-read it into memory? I would keep the frame definitions in memory for use in compare after loading rather than reading them back in.

I don't really see a reason for this to be a class at all rather than just a trio of functions, but maybe if you have to read multiple files with mildly varying formats you could get some benefit of using class attributes to define the format while inheriting the general logic.

Answer 2

One of the more powerful aspects of Python is that you can return something called a tuple. To answer this in a more generic Python sense consider this code:

>>> def load(file1, file2):
        return file1+'.txt',file2+'.txt'

>>> def convert(file1, file2):
        return 'converted_'+file1,'converted_'+file2

>>> convert(*load("Java", "C#"))
('converted_Java.txt', 'converted_C#.txt')

Each function takes two named arguments, but the returned tuple of the first can be "unpacked" into the input arguments of the second by adding a * in front of it.

Answer 3

I might be totally off here, but why don't you do it exactly as you're saying?

Just call self.compare() out of your load() method.

You can also add return statements to load() and return a tuple with the files.

Then add a 4th method to your class, which then collects the returned files and pipes them to the compare() method.

Best Regards!

Answer 4

Do you mean call with the name of the two files? Well you defined a class, so you can just do:

def load(self, fileIn1, fileIn2, fileOut1, fileOut2):
    ... // do stuff here
    // when done
    self.compare( fileOut1, fileOut2 )

And so on.