clean.py

def startsWithDateAndTime(s):
    # regex pattern for date.(Works only for android. IOS Whatsapp export format is different. Will update the code soon
    pattern = '^([0-9]+)(\/)([0-9]+)(\/)([0-9][0-9]), ([0-9]+):([0-9][0-9]) (AM|PM) -'
    result = re.match(pattern, s)
    if result:
        return True
    return False
  
# Finds username of any given format.
def FindAuthor(s):
    patterns = [
        '([\w]+):',                        # First Name
        '([\w]+[\s]+[\w]+):',              # First Name + Last Name
        '([\w]+[\s]+[\w]+[\s]+[\w]+):',    # First Name + Middle Name + Last Name
        '([+]\d{2} \d{5} \d{5}):',         # Mobile Number (India)
        '([+]\d{2} \d{3} \d{3} \d{4}):',   # Mobile Number (US)
        '([\w]+)[\u263a-\U0001f999]+:',    # Name and Emoji              
    ]
    pattern = '^' + '|'.join(patterns)
    result = re.match(pattern, s)
    if result:
        return True
    return False
  
def getDataPoint(line):   
    splitLine = line.split(' - ') 
    dateTime = splitLine[0]
    date, time = dateTime.split(', ') 
    message = ' '.join(splitLine[1:])
    if FindAuthor(message): 
        splitMessage = message.split(': ') 
        author = splitMessage[0] 
        message = ' '.join(splitMessage[1:])
    else:
        author = None
    return date, time, author, message

parsedData = [] # List to keep track of data so it can be used by a Pandas dataframe
# Upload your file here
conversationPath = '/content/WhatsApp Chat with Blabla (1).txt' # chat file
with open(conversationPath, encoding="utf-8") as fp:
    fp.readline() # Skipping first line of the file because contains information related to something about end-to-end encryption
    messageBuffer = [] 
    date, time, author = None, None, None
    while True:
        line = fp.readline() 
        if not line: 
            break
        line = line.strip() 
        if startsWithDateAndTime(line): 
            if len(messageBuffer) > 0: 
                parsedData.append([date, time, author, ' '.join(messageBuffer)]) 
            messageBuffer.clear() 
            date, time, author, message = getDataPoint(line) 
            messageBuffer.append(message) 
        else:
            messageBuffer.append(line)
   
df = pd.DataFrame(parsedData, columns=['Date', 'Time', 'Author', 'Message']) # Initialising a pandas Dataframe.
df["Date"] = pd.to_datetime(df["Date"])

First, thanks for sharing this code and the great article on Medium!
I think you're forgetting to add the last row of the file to 'df'. What you could do to fix it is simply adding lines 51 and 52 just before the break in line 48 (otherwise the last line is not added to parsedData).
Other than that - great job, and thanks again!

It's a very honour to share your code with us. I found one difficulty while uploading my .txt file can anyone solve this problem