How to write a string 'a<b<C' in a text file in Python?

See more:

Python

Python3.6

I have to write strings like a<b<c in a text file from the dictionary PDP_data_listt, which looks like this:

PDP_data_listt = {
"['2','3','4']": [
(
[('a', 'b', -1), ('a', 'c', -1), ('b', 'c', 1)],
[('a', 'b', -1), ('a', 'c', -1), ('b', 'c', -1)]
),
(
[('a', 'b', -1), ('a', 'c', -1), ('b', 'c', -1)],
[('a', 'b', -1), ('a', 'c', -1), ('b', 'c', -1)]
),
(
[('a', 'b', -1), ('a', 'c', -1), ('b', 'c', -1)],
[('a', 'b', -1), ('a', 'c', -1), ('b', 'c', -1)]
)
],
"['2', '3', '5']": [
(
[('a', 'b', -1), ('a', 'c', -1), ('b', 'c', 1)],
[('a', 'b', -1), ('a', 'c', -1), ('b', 'c', 1)]
),
(
[('a', 'b', -1), ('a', 'c', -1), ('b', 'c', 1)],
[('a', 'b', -1), ('a', 'c', -1), ('b', 'c', 1)]
),
(
[('a', 'b', -1), ('a', 'c', -1), ('b', 'c', 1)],
[('a', 'b', -1), ('a', 'c', -1), ('b', 'c', 1)]
),
(
[('a', 'b', -1), ('a', 'c', -1), ('b', 'c', 1)],
[('a', 'b', -1), ('a', 'c', -1), ('b', 'c', 1)]
)
]
}

Here the key "['2','3','4']" consists nine lists of tuples' lists. These lists describe the comparative relation between the key's elements.

For instance, the first list [('a', 'b', -1), ('a', 'c', -1), ('b', 'c', 1)] shows the relations as a<b, a<c, and b>c. Collectively, we can say that a<c<b or '2'<'4'<'3'. The value -1 shows that the first element a is less than the second element b. The value '1' shows that the first element is greater than the second element. A value '0' shows that both elements are equal. Now the problem is that I want to save the combined relation a<c<b or 2<4<3 in the text file for each key of the dictionary, instead of saving the individual relations.

How could I save the combined relation in a text file in python?

What I have tried:

I have already saving the individual relations using the following code.

for PDP_fragment in PDP_data_listt:  # for each fragment a different text file

    text_file = open(str(name) + '/PDP_ordering/' + (str(file_n)+' cars '+ str(PDP_fragment) + '.txt'),
                     'w')  # the writing of a file
    text_file.write(str(PDP_fragment) + '= [a, b, c, etc.]' + '\n\n\n')
    for matrix in PDP_data_listt[PDP_fragment]:  # add every matrix of the fragment to the file
        if PDP_m=='static':
            text_file.write( 'at '+str('timestamp')'+'\n')
            for d_in in range(len(matrix)):
                text_file.write('d' + str(d_in + 1) + ': ' + str(matrix[d_in]) + '\n\n')  # the matrix is printed
            text_file.write('\n\n') # the matrix is printed

Currently, I am writing only the individual relations but couldn't find a way to write the combined relation.