write header rows to csv python

Question

How do I add headers to row one in a csv?

My solution currently appends everything

Something like: writer.writerow(['DataA', 'DataB', 'DataC', 'DATA D'])[0]

I feel like there an easy way of doing this and I'm overlooking the obvious.

I've looked at a lot of examples online but am still struggling as to how you can easily do this in a csv.

As an example lets say I wanted to scrape data of SO - load up selenium, write that into four columns and do this for 20 pages. I'd want to write the headers to row 1 each time and then append the scraped data

with open('C:\\fa.csv', 'a+', newline='', encoding="utf-8") as outfile:
    writer = csv.writer(outfile)
    writer.writerow(['DataA', 'DataB', 'DataC', 'DataD'])
    for row in zip(ZAW_text, RESULTS1, RESULTS):
        writer.writerow(row)
        #writer.writerows({'Date': row[0], 'temperature 1': row[1], 'temperature 2': 0.0} for row in writer)
        print(row)

That is pretty much how you do it. I don't think there is an easier way. — AtHeartEngineer
– AtHeartEngineer, Commented Dec 1, 2017 at 8:32
@Tyler.Exposure Very well. Well in my case it appends the headers so it's not working for me. How do I get around that as I want headers in row one. — user8900239
– user8900239, Commented Dec 1, 2017 at 8:34
Pretty sure I'm missing something. You can specify columns in csv surely rows is possible too. — user8900239
– user8900239, Commented Dec 1, 2017 at 8:37

AtHeartEngineer · Accepted Answer · 2017-12-01 08:56:43Z

3

import csv
import os

file_name = 'C:\\fa.csv'
fake_data = [[1, 2, 3, 4, 5, 4444, 6, 67], [1, 2, 3, 4, 5, 4444, 6, 67],
             [1, 2, 3, 4, 5, 4444, 6, 67], [1, 2, 3, 4, 5, 4444, 6, 67]]
headers = ['DataA', 'DataB', 'DataC', 'DataD']

if os.path.isfile(file_name):
  with open(file_name, 'a', encoding="utf-8") as outfile:
    writer = csv.writer(outfile)
    for datum in fake_data:
      writer.writerow(datum)
else:
  with open(file_name, 'w', encoding="utf-8") as outfile:
    writer = csv.writer(outfile)
    writer.writerow(headers)
    for datum in fake_data:
      writer.writerow(datum)

In the first line open('C:\\fa.csv', 'a+', newline='', encoding="utf-8") you have a+ which is append you want w which is write.

Check this out: https://docs.python.org/3/tutorial/inputoutput.html#reading-and-writing-files

edited Dec 1, 2017 at 8:56

answered Dec 1, 2017 at 8:42

AtHeartEngineer

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7 Comments

user8900239 Over a year ago

I see. In the example with 20 other pages, will that data still be appended in the csv. Or will it all overwrite each other.

user8900239 Over a year ago

Unfortunately. The headers need to be at row 1. The data needs to be appended as its in a loop

AtHeartEngineer Over a year ago

Every time you run this whole function, it will overwrite the file, but as its going through the for loop it will append, because you are writing a new row each time. Make sense?

user8900239 Over a year ago

Uh.. that makes sense. I'd rather not overwrite the file if possible and keep an ever growing list of data. Is that possible? Hmm

AtHeartEngineer Over a year ago

So, this basically checks if the file exists, if it exists, then it will only append to it, if it doesn't exist, it will write the header row, then continue writing new rows to it.

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