Comparing two lists items in python

Question

Hi, I have two files which I loaded into lists. The content of the first file is something like this:

d.complex.1
23
34
56
58
68
76
.
.
.
etc
d.complex.179
43
34
59
69
76
.
.
.
etc

The content of the second file is also the same but with different numerical values. Please consider from one d.complex.* to another d.complex.* as one set.

Now I am interested in comparing each numerical value from one set of first file with each numerical value of the sets in the second file. I would like to record the number of times each numerical has appeared in the second file overall.

For example, the number 23 from d.complex.1 could have appeared 5 times in file 2 under different sets. All I want to do is record the number of occurrences of number 23 in file 2 including all sets of file 2.

My initial approach was to load them into a list and compare but I am not able to achieve this. I searched in google and came across sets but being a python noob, I need some guidance. Can anyone help me?

If you feel the question is not clear,please let me know. I have also pasted the complete file 1 and file 2 here:

http://pastebin.com/mwAWEcTa http://pastebin.com/DuXDDRYT

Answer 1

First create a function which can load a given file, as you may want to maintain individual sets and also want to count occurrence of each number, best would be to have a dict for whole file where keys are set names e.g. complex.1 etc, for each such set keep another dict for numbers in set, below code explains it better

def file_loader(f):
    file_dict = {}
    current_set = None
    for line in f:
        if line.startswith('d.complex'):
            file_dict[line] = current_set = {}
            continue

        if current_set is not None:
            current_set[line] = current_set.get(line, 0)

    return file_dict

Now you can easily write a function which will count a number in given file_dict

def count_number(file_dict, num):
    count = 0
    for set_name, number_set in file_dict.iteritems():
        count += number_set.get(num, 0)

    return count

e.g here is a usage example

s = """d.complex.1
10
11
12
10
11
12"""

file_dict = file_loader(s.split("\n"))
print file_dict
print count_number(file_dict, '10')

output is:

{'d.complex.1': {'11': 2, '10': 2, '12': 2}}
2

You may have to improve file loader, e.g. skip empty lines, convert to int etc

Answer 2

Open the file using Python's open function, then iterate over all its lines. Check whether the line contains a number, if so, increase its count in a defaultdict instance as described here.

Repeat this for the other file and compare the resulting dicts.