Cleaned up implementation of POST request driver code for /timespent/ view.

timespent.py

from io import TextIOWrapper
from datetime import datetime
from collections import Counter, defaultdict

import csv
import re

time = request.POST['time']
lower = request.POST['lower']
if lower.isdigit():
    lower = int(lower)
else:
    lower = 0
time = datetime.strptime(time, "%H:%M")
meeting_end_time = time.strftime("%I:%M:%S %p")
FMT = '%I:%M:%S %p'
data = list(
    TextIOWrapper(request.FILES['csv_file1'].file, encoding='cp1252'))

attendees = []
for line in data:
    attendees.append(line)
attendees.pop(0)

# removes '\x00' from all strings in list of strings
attendees = [x.replace('\x00', '') for x in attendees]

# removes '\n' occurances in list of strings
attendees = list(filter(('\n').__ne__, attendees))

# removes '\n' from end of all strings in list of strings
attendees = [x.split('\n')[0] for x in attendees]

# calculates length of all strings in list of strings if len = 0 therefore strings is empty
sizes = [len(x) for x in attendees]

# remove the empty strings by its index from sizes list
for _ in range(len(sizes)):
    if (sizes[_] == 0):
        attendees.pop(_)

# converting list separated into string separated for performing regex op
converted_string = []
for i in attendees:
    x = ''
    for j in i:
        x += j
    converted_string.append(x)

# extracting all attendees names from converted_string
attendee_name = []
for i in converted_string:
    x = re.search(r"(.*?)Joined", i)
    if x:
        attendee_name.append(
            i[x.start():x.end()].split('Joined')[0][:-1])
    else:
        x = re.search(r"(.*?)Left", i)
        attendee_name.append(
            i[x.start():x.end()].split('Left')[0][:-1])

# Extracting status of attendees:
attendee_status = []
for i in converted_string:
    if ("Joined before" in i):
        attendee_status.append("Joined")
    elif ("Joined" in i):
        attendee_status.append("Joined")
    else:
        attendee_status.append("Left")

# Extracting Time and date of attendees:
attendee_date_time = []
for i in converted_string:
    if ("Joined before" in i):
        attendee_date_time.append(i.split("Joined before")[1])
    elif ("Joined" in i):
        attendee_date_time.append(i.split("Joined")[1])
    else:
        attendee_date_time.append(i.split("Left")[1])

#check if the uploaded data is in 24/12 hour format
if (attendee_date_time[0][-1].isdigit()):
    twelve = False
    # Extracting date from attendee_date_time
    attendee_date = []
    for i in attendee_date_time:
        x = i[1:]
        attendee_date.append(x.split(' ', 1)[0])

    # Extracting time from attendee_date_time
    attendee_time24 = []

    for i in attendee_date_time:
        attendee_time24.append(i.split(' ', 1)[1])

    attendee_time = []

    for i in attendee_time24:
        tm = datetime.strptime(i, "%H:%M:%S")
        attendee_time.append(tm.strftime("%I:%M:%S %p"))

else:
    twelve = True
    # Extracting date from attendee_date_time
    attendee_date = []
    for i in attendee_date_time:
        x = i[1:]
        attendee_date.append(x.split(' ', 1)[0])
    # Extracting time from attendee_date_time
    attendee_time = []

    for i in attendee_date_time:
        x = i[1:-1]
        if (x[len(x) - 1] != "M"):
            x += "M"  # adds "M" at the end if condition is true
        attendee_time.append(x.split(' ', 1)[1])

# converting output into list of tuples
complete_list_dup = list(
    map(
        tuple,
        zip(attendee_name, attendee_status, attendee_date,
            attendee_time)))

# removing major bug caused by people joining by 2+ devices
"""
complete_list_dup -> List with adjacent "Joined" and "Left"
complete_list_dup1 -> List with adjacent "Joined" eliminated but "Left" still there (reversed for latter elimination)
complete_list -> List with both adjacent "Joined" and "Left" eliminated
"""
complete_list_dup1 = []
complete_list_dup1.append(complete_list_dup[0])

for i in range(len(complete_list_dup)):
    if (complete_list_dup[i][0] == complete_list_dup1[-1][0]):
        if (complete_list_dup[i][1] == complete_list_dup1[-1][1] ==
                "Joined"):
            pass
        else:
            complete_list_dup1.append(complete_list_dup[i])
    else:
        complete_list_dup1.append(complete_list_dup[i])

#reversing the list so that I only keep 1st occurance of "Left"
complete_list_dup1.reverse()

complete_list = []
complete_list.append(complete_list_dup1[0])

for i in range(len(complete_list_dup1)):
    if (complete_list_dup1[i][0] == complete_list[-1][0]):
        if (complete_list_dup1[i][1] == complete_list[-1][1] ==
                "Left"):
            pass
        else:
            complete_list.append(complete_list_dup1[i])
    else:
        complete_list.append(complete_list_dup1[i])

#reversing the list back to original state.
complete_list.reverse()

# Counting the number of instances of single attendee
instances = Counter(elem[0] for elem in complete_list)

# converting Counter output to list of tuples
instances_list = []
for (i, j) in instances.items():
    instances_list.append((i, j))

# segrating attendees based on partial and full information available
attendee_partial = []
attendee_full = []
for (i, j) in instances_list:
    if (j % 2 == 0):
        attendee_full.append((i, j))
    else:
        attendee_partial.append((i, j))

# appending attendees in the list with all of their information (full)
attendee_full_list = []
for (i, j) in attendee_full:
    for (name, status, date, time) in complete_list:
        if (name == i):
            attendee_full_list.append((name, status, date, time))

# appending attendees in the list with all of their information (partial)
attendee_partial_list = []
for (i, j) in attendee_partial:
    for (name, status, date, time) in complete_list:
        if (name == i):
            attendee_partial_list.append((name, status, date, time))

# calculating time for each attendee with instances >=2, via iterating over an attendee >> might return more than one entry for single attendee if instances > 2

name_timespent_full = []

for _ in range(0, len(attendee_full_list) - 1, 2):
    name_timespent_full.append(
        (attendee_full_list[_][0],
         (datetime.strptime(attendee_full_list[_ + 1][3], FMT) -
          datetime.strptime(attendee_full_list[_][3],
                            FMT)).total_seconds()))

# adding total time spent values from all instances obtained from above operation
attendee_full_list_sum = defaultdict(int)
for i, k in name_timespent_full:
    attendee_full_list_sum[i] += k

# Scraping partial list with instances = 1
attendee_partial_list_one = []
for (i, j) in attendee_partial:
    if (j == 1):
        attendee_partial_list_one.append((i, j))

# Scraping partial list with instances > 2
attendee_partial_list_greater = []
for (i, j) in attendee_partial:
    if (j > 2):
        attendee_partial_list_greater.append((i, j))

# Creating a list which includes attendees with instances of 1 and every last instance of an attendee

attendee_partial_list_stray = []

# appending every attendee with one instance to list
for (i, j) in attendee_partial_list_one:
    for _ in range(len(attendee_partial_list)):
        if (i == attendee_partial_list[_][0]):
            attendee_partial_list_stray.append(
                (attendee_partial_list[_][0],
                 attendee_partial_list[_][1],
                 attendee_partial_list[_][2],
                 attendee_partial_list[_][3]))

# appending every last attendee with odd instance to list
for (i, j) in attendee_partial_list_greater:
    for _ in range(len(attendee_partial_list) - 1):
        if (i == attendee_partial_list[_][0]):
            if (attendee_partial_list[_][0] == attendee_partial_list[
                    _ + 1][0]):
                pass
            else:
                attendee_partial_list_stray.append(
                    (attendee_partial_list[_][0],
                     attendee_partial_list[_][1],
                     attendee_partial_list[_][2],
                     attendee_partial_list[_][3]))

# making a full list of separated partial attendees to be even attendees
attendee_partial_list_even = []
for (i, j) in attendee_partial_list_greater:
    for _ in range(len(attendee_partial_list) - 1):
        if (i == attendee_partial_list[_][0]):
            if (attendee_partial_list[_][0] == attendee_partial_list[
                    _ + 1][0]):
                attendee_partial_list_even.append(
                    (attendee_partial_list[_][0],
                     attendee_partial_list[_][1],
                     attendee_partial_list[_][2],
                     attendee_partial_list[_][3]))

# calculating time for partial even list
attendee_partial_list_even_time = []
for _ in range(0, len(attendee_partial_list_even) - 1, 2):
    attendee_partial_list_even_time.append((
        attendee_partial_list_even[_][0],
        (datetime.strptime(attendee_partial_list_even[_ + 1][3], FMT) -
         datetime.strptime(attendee_partial_list_even[_][3],
                           FMT)).total_seconds()))

# calculating time for partial stray list
attendee_partial_list_stray_time = []

for _ in range(0, len(attendee_partial_list_stray)):
    attendee_partial_list_stray_time.append(
        (attendee_partial_list_stray[_][0],
         (datetime.strptime(meeting_end_time, FMT) - datetime.strptime(
             attendee_partial_list_stray[_][3], FMT)).total_seconds()))

final_strays_list = []

attendee_partial_list_stray_time = attendee_partial_list_stray_time + \
    attendee_partial_list_even_time

attendee_partial_list_sum = defaultdict(int)
for i, k in attendee_partial_list_stray_time:
    attendee_partial_list_sum[i] += k

attendee_partial_list_sum.update(attendee_full_list_sum)
final_list = []

for i in attendee_partial_list_sum:
    final_list.append((i, round(attendee_partial_list_sum[i] / 60)))

# To print list in console
# for (i, j) in final_list:
#     print(i, j)
final_list.sort(key=lambda x: x[0])  # sorts on A - Z increasing
final_list.sort(key=lambda x: x[1],
                reverse=True)  # sorts on time decreasing

total = len(final_list)  #returns total attendees
if twelve:
    date = attendee_date[0][:-1]
else:
    date = attendee_date[0][:-1]

context = {
    'member_list': final_list,
    'time': meeting_end_time,
    'total': total,
    'date': date,
    'lower': lower,
}

https://miraaj-timespent.herokuapp.com/timespent/