DataFrame.assign(**kwargs) It accepts a keyword & value pairs, where a keyword is column name and value is either list / … Basically, it gets updated each time I run the Python script. Right now I am storing the old csv rows values in a list and then deleting the csv file and creating it again with the new list value. Code faster with the Kite plugin for your code editor, featuring Line-of-Code Completions and cloudless processing. The column has no name, and i have problem to add the column name, already tried reindex, pd.melt, rename, etc. Add a new column in pandas python using existing column. If you want that cell value doesn't gets copy, so first of all create a empty Column in your csv file manually, like you named it as Hours then, Now for this you can add this line in above code, csv_input['New Value'] = csv_input['Hours'] or simply we can, without adding the manual column, we can. If not, check that post out! Open ‘input.csv’ file in read mode and create csv.reader object for this csv file. not new columns. it should look like this: id, header1, header2, header1_1, header1_2, header1_3 Python: Add a column to an existing CSV file; Python: How to unzip a file | Extract Single, multiple or all files from a ZIP archive Right now this code will write three columns of data: I know if you open the file as "A" it will append the file, but I only know how to use it to add new rows to the document. In Python, Pandas Library provides a function to add columns i.e. I have a csv file which is usually has between 100 and 200 columns. To the existing dataframe, lets add new column named “Total_score” using by adding “Score1” and “Score2” using apply() function as shown below #### new columns based on existing columns df['Total_Score'] = df.apply(lambda row: row.Score1 + row.Score2, axis = 1) df csv_input['New Value'] = '' #simple and easy Output: Method #4: By using a dictionary We can use a Python dictionary to add a new column in pandas DataFrame. I have a new column of data that I want to add to the csv file. Use an existing column as the key values and their respective values will be the values for new column. After reading your data from a CSV file, renaming the column, and adding a new column, you also may need to change your data types to numeric. Kite is a free autocomplete for Python developers. I am trying to add a new row to my old csv file. I am new to python and I have a csv file of the following type id, header1, header2 1, 80-80-20, a 2, 30,b 3,,c 4,60-20,d Now I would like to separate the values in header1 to new columns where the -is the "delimiter", i.e. Python: How to create a zip archive from multiple files or Directory; Python : How to remove a file if exists and handle errors | os.remove() | os.ulink() Python: How to append a new row to an existing csv file? How do I add a new column to an already existing csv file and add unique values to each line of the new column for the length of the csv file? Check out the newer post, about this topic, to learn more about converting columns in Python. Wanted to know are there any better ways of doing this. 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