How to append a new row to an existing csv file?
For appending a new row to an existing CSV file we have many ways to do that. Here we will discuss 2 ways to perform this task effectively. So, we have 2 ways first is ‘Append a list as a new row to the existing CSV file’ and the second way is ‘Append a dictionary as a new row to the existing CSV file’.
First, let’s have a look at our existing CSV file contents. Suppose we have CSV file event.csv which has the below contents.
CSV file before append
For writing a CSV file, the CSV module provides two different classes writer and Dictwriter.
Append a list as a new row to the existing CSV file
let’s see how to use writer class to append a list as a new row into an existing CSV file. There are several steps to take that.
- Import writer class from csv module
- Open your existing CSV file in append mode
Create a file object for this file. - Pass this file object to csv.writer() and get a writer object.
- Pass the list as an argument into the writerow() function of the writer object.
(It will add a list as a new row into the CSV file). - Close the file object
Let’s take one List that we want to add as a new row.
List=[6,'William',5532,1,'UAE']
Now apply the above steps to the program.
- Python3
# Import writer class from csv modulefrom csv import writer # List List=[6,'William',5532,1,'UAE'] # Open our existing CSV file in append mode# Create a file object for this filewith open('event.csv', 'a') as f_object: # Pass this file object to csv.writer() # and get a writer object writer_object = writer(f_object) # Pass the list as an argument into # the writerow() writer_object.writerow(List) #Close the file object f_object.close() |
Output:
CSV file After appending List
When you are executing this program Ensure that your CSV file must be closed otherwise this program will give you a permission error.
Append a dictionary as a new row to the existing CSV file
let’s see how to use DictWriter class to append a dictionary as a new row into an existing CSV file. There are several steps to do that.
- Import DictWriter class from CSV module.
- Open your CSV file in append mode
Create a file object for this file. - Pass the file object and a list of column names to DictWriter()
You will get a object of DictWriter. - Pass the dictionary as an argument to the Writerow() function of DictWriter
(it will add a new row to CSV file). - Close the file object
Let’s take one Dictionary that we want to add as a new row.
dict={'ID':6,'NAME':'William','RANK':5532,'ARTICLE':1,'COUNTRY':'UAE'}
Now apply the above steps to the program.
- Python3
# Import DictWriter class from CSV modulefrom csv import DictWriter # list of column names field_names = ['ID','NAME','RANK', 'ARTICLE','COUNTRY'] # Dictionarydict={'ID':6,'NAME':'William','RANK':5532, 'ARTICLE':1,'COUNTRY':'UAE'} # Open your CSV file in append mode# Create a file object for this filewith open('event.csv', 'a') as f_object: # Pass the file object and a list # of column names to DictWriter() # You will get a object of DictWriter dictwriter_object = DictWriter(f_object, fieldnames=field_names) #Pass the dictionary as an argument to the Writerow() dictwriter_object.writerow(dict) #Close the file object f_object.close() |
Output:
CSV file after Appending Dictionary
When you are executing this program ensures that your CSV file must be closed otherwise this program will give you a permission error.
Last Updated on November 13, 2021 by admin