Sorting and Grouping Nested Lists Consists of Class Objects

Question

I have hundreds of text files that i need to parse according to the username and the date. I tried to put useful data in the text files in lists like that:

    [
      ['[email protected]', '34209809' '1434546354', '2016-07-18 00:20:58'], 
      ['[email protected]', '234534345', '09402380',, '2016-07-18 00:20:03'], 
      ['[email protected]', '345315531','1098098098', '2016-07-18 02:40:00'], 
      ['[email protected]', '345431353', '231200023', '2016-07-18 15:45:49'], 
      ['[email protected]', '23232424', '234809809', '2016-07-18 20:45:40']
    ]

However, I would like to sort them according to the datetime and group by usernames so the output will be like:

    [
     ['[email protected]', '23232424', '234809809', '2016-07-18 20:45:40'],
     ['[email protected]', '34209809' '1434546354', '2016-07-18 00:20:58'],
     ['[email protected]', '345431353', '231200023', '2016-07-18 15:45:49'],
     ['[email protected]', '234534345', '09402380',, '2016-07-18 00:20:03'],
     ['[email protected]', '345315531','1098098098', '2016-07-18 02:40:00']
    ]

Here is my code:

    import glob
    from operator import itemgetter
    from itertools import groupby
    def read_large_file(filename):
        matrix=[]
        global username
        username=[]
        for myfile in glob.glob(filename):
            infile = open(myfile, "r")
            for row in infile:
                row=row.strip()
                array=row.split(';') 
                username.append(array[9])
                matrix.append(cdr(array[9],array[17],array[18],array[8]))

        return matrix


    class cdr(object):               
        def__init__(self,username,total_seconds_since_start,download_bytes,date_time):
            self.username=username
            self.total_seconds_since_start=total_seconds_since_start
            self.download_bytes=download_bytes
            self.date_time=date_time


    def GroupByUsername(matrix):
        new_matrix=[]
        new_matrix=groupby(matrix, itemgetter(0))
        return new_matrix

    matrix=read_large_file('C:\Users\ceren\.spyder2/test/*')
    matrix_new=GroupByUsername(matrix)

I tried to use the solution in this link : Sorting and Grouping Nested Lists in Python however i've got these errors:

   'cdr' object does not support indexing
   'cdr' object is not iterable

Karin · Accepted Answer · 2016-08-08 07:06:37Z

2

You can probably just use the simple Python built-in sort.

sorted_list = sorted(data, key=lambda user_info: (user_info[0], user_info[3]))

The lambda key tells Python how to sort the list (ascending). For each entry in data, user_info will be the list of 4 attributes. So, user_info[0] will be the email, and user_info[3] will be the datetime.

edited Aug 8, 2016 at 7:06

answered Aug 8, 2016 at 6:52

Karin

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6 Comments

CerenH Over a year ago

Thank youu, i tried however i got this error: TypeError: <lambda>() takes exactly 1 argument (2 given)

Karin Over a year ago

Ah sorry, I forgot the key=. I've fixed it - give it a try :)

CerenH Over a year ago

Still have this: TypeError: 'cdr' object does not support indexing , i think python does not let me to put class objects in list indexes.

juanpa.arrivillaga Over a year ago

If you want to replicate exactly the output you're going to want something like sorted(sorted(data, key=lambda x: x[-1], reverse=True), key=lambda x:x[0]) since Timsort is stable.

Karin Over a year ago

The solution I gave will sort the nested list you provided. To sort a list of cdr objects, you will want: sorted_list = sorted(cdr_list, key=lambda cdr: (cdr.username, cdr.date_time))

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