How to add timestamp to CSV file in Python

23 Aug, 2021
Prerequisite: Datetime module
In this example, we will learn How to add timestamp to CSV files in Python. We can easily add timestamp to CSV files with the help of datetime module of python. Let’s the stepwise implementation for adding timestamp to CSV files in Python.
Import csv and datetime module. We will use the csv module to read and write the csv file and datetime module to add the current date and time in the csv file
Take the data from the user.
Open the CSV file in read and write mode (‘r+’) using open() function.The open() function opens a file and returns its as a file-object.newline = ‘ ‘ controls how universal newlines mode works. It can be None, ‘ ‘, ‘\n’, ‘\r’, and ‘\r\n’.write() returns a writer object which is responsible for converting the user’s data into a delimited string.
The open() function opens a file and returns its as a file-object.
newline = ‘ ‘ controls how universal newlines mode works. It can be None, ‘ ‘, ‘\n’, ‘\r’, and ‘\r\n’.
write() returns a writer object which is responsible for converting the user’s data into a delimited string.
Get current date and time using the datetime.now() function of datetime module.
Iterate over all the data in the rows variable with the help of a for loop.
Insert the current date and time at 0th index in every data using the insert() function.
Write the data using writerow() in the CSV file with the current date and time. 
Example 1: Add timestamp to CSV file
Python3
# Importing required modulesimport csvfrom datetime import datetime    # Here we are storing our data in a# variable. We'll add this data in# our csv filerows = [['GeeksforGeeks1', 'GeeksforGeeks2'],        ['GeeksforGeeks3', 'GeeksforGeeks4'],        ['GeeksforGeeks5', 'GeeksforGeeks6']]  # Opening the CSV file in read and# write mode using the open() modulewith open(r'YOUR_CSV_FILE.csv', 'r+', newline='') as file:      # creating the csv writer    file_write = csv.writer(file)      # storing current date and time    current_date_time = datetime.now()      # Iterating over all the data in the rows     # variable    for val in rows:                  # Inserting the date and time at 0th         # index        val.insert(0, current_date_time)                  # writing the data in csv file        file_write.writerow(val)
Output :
Example  2: Adding timestamp to CSV file
Python3
# Importing required modulesimport csvfrom datetime import datetime    # function to write in csv filedef write_in_csv(rows):      # Opening the CSV file in read and    # write mode using the open() module    with open(r'YOUR_CSV_FILE.csv', 'r+', newline='') as file:          # creating the csv writer        file_write = csv.writer(file)          # Iterating over all the data in the rows         # variable        for val in rows:                        # writing the data in csv file            file_write.writerow(val)    # list to store the values of the rowsrows = []  # while loop to take# inputs from the userrun = ''while run != 'no':      # lists to store the user data    val = []      # Taking inputs from the user    val1 = input("Enter 1st value:- ")    val2 = input("Enter 2nd value:- ")    val3 = input("Enter 3rd value:- ")      # storing current date and time    current_date_time = datetime.now()      # Appending the inputs in a list    val.append(current_date_time)    val.append(val1)    val.append(val2)    val.append(val3)      # Taking input to add one more row    # If user enters 'no' then the will loop will break    run = input("Do you want to add one more row? Type Yes or No:- ")    run = run.lower()      # Adding the stored data in rows list    rows.append(val)  # Calling function to write in csv filewrite_in_csv(rows)
Output:
It is also possible to add timestamp to a CSV file that already contains some data. For this open the first file in read mode and the second file in write mode. Creating a csv reader object of the first file using the reader() function of csv module. reader() return a reader object which will iterate over lines in the given CSV file.
Append every data stored in the first file in rows variable using a for loop. Create a writer object of the second file using the writer() function of csv module. Now iterate over all the data in the rows variable using a for loop. Store the current date and time in a variable and then inserting it in the data at 0th index using the insert() function. Write the stored data in File2 using the writerow() function of csv module. 
Example 1: Adding timestamp to existing data
Content of File1:
Python3
# Importing required modulesimport csvfrom datetime import datetime    # creating a list to store the# existing data of CSV filerows = []  # Opening the CSV file in read mode using # the open() modulewith open(r'FILE1.csv', 'r', newline='') as file:          # Opening another CSV file to in write mode     # to add the data    with open(r'FILE2.csv', 'w', newline='') as file2:          # creating the csv reader        reader = csv.reader(file, delimiter=',')          # storing the data of the csv file in a list        for row in reader:            rows.append(row)           # creating the csv writer        file_write = csv.writer(file2)          # Iterating over all the data in the rows        # variable        for val in rows:              # storing current date and time in a            # variable            current_date_time = datetime.now()            val.insert(0, current_date_time)                          # writing the data in csv file            file_write.writerow(val)
Output:
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