How to append new rows in CSV file python?

Question

I'm using python 2.7 and I have a program that when I take picture from the camera ,the data(phase,date,time,name of image) will be stored in CSV file each time when the image being capture. This is the csv file looks like when the short code below executed. https://i.stack.imgur.com/hzMTe.png

As you can see the "headers" which are 'Phase', 'Date', 'Time','Name' will be printed out again in the next line when the image being capture.

I want the headers just print one time on the top of csv file. As I strolling around some websites there is [newline=''] keyword that should work but as I'm using python 2.7 it's not possible.

Any help would be greatly appreciated.

import csv

with open('data.csv', 'a') as f:

                fieldnames = ['Phase', 'Date', 'Time','Name']
                thewriter = csv.DictWriter(f, fieldnames = fieldnames)
                thewriter.writeheader()

                thewriter.writerow({'Phase': _phase, 'Date' : 
                 _currentDT.date(), 'Time' : _currentDT.time(),
                                    'Name' : _nameImage })

You can maybe compare the first row and see if headers are added and not add it the second time — Z.Amir, May 10 '19 at 10:56
See this : https://stackoverflow.com/questions/32312309/check-if-header-exists-with-python-pandas?lq=1 — Z.Amir, May 10 '19 at 11:01

Z.Amir · Answer 1 · 2019-05-13T09:26:42.640

0

If you want a simple solution you can do something like this (not the most efficient solution)

import csv

with open('data.csv', 'r+') as f:
    reader = csv.reader(f)
    row1 = []

    try:
        row1 = next(reader)
    except StopIteration:
        print("No data is written to file yet")

    fieldnames = ['Phase', 'Date', 'Time', 'Name']
    thewriter = csv.DictWriter(f, fieldnames=fieldnames)

    if row1 != fieldnames:
        thewriter.writeheader()

    thewriter.writerow({'Phase': _phase, 'Date' : 
     _currentDT.date(), 'Time' : _currentDT.time(),'Name' : _nameImage })

edited May 13 '19 at 09:26

answered May 10 '19 at 11:40

Z.Amir

195
1
12

sorry for late reply, but your code doesn't work, it somehow isn't write anything, just an empty csv file. – frankenstein May 13 '19 at 09:01
the code runs without any error, but somehow the csv file was empty as this link. https://imgur.com/r8bnUWO – frankenstein May 13 '19 at 09:18
```StopIteration``` exception was thrown which I was not handling previously. – Z.Amir May 13 '19 at 09:30
I have updated your code but when I run it it's not even write the file which is data.csv – frankenstein May 13 '19 at 09:45
but I have tried to create a "data.csv" by hand before I execute the code , and the data is written lol , as this https://imgur.com/KLerJUP – frankenstein May 13 '19 at 09:50
This code above works fine for me. Does it give any error ? Can you check your logs ? – Z.Amir May 13 '19 at 09:50
@huyhoangle is this not what you wanted ? – Z.Amir May 13 '19 at 09:51
@huyhoangle the code works fine and gives a csv file which is comma separated. You can open this file in excel or any datasheet tool. You can read this file in python like csv – Z.Amir May 13 '19 at 09:56
The problem is I will have to create the csv file prior otherwise your code is not going to write anything. – frankenstein May 13 '19 at 09:57
You can easily check if file exists and then create one if it doesn't. That wasn't the Acceptance Criteria for this question – Z.Amir May 13 '19 at 10:01
ah got it. thank for the code, really appreciate it. :D – frankenstein May 13 '19 at 10:02

How to append new rows in CSV file python?

1 Answers1