Append Dictionary or list of values at the end of each row in csv using python

Question

I want to append a list of values at the end of each row of a csv file except the header.

I have tried following code but it deletes all the rows from csv file and does not appends any value to the csv file.

import tensorflow
from fer.fer import FER
import cv2
from os import listdir
from os.path import isfile, join
import numpy
import csv



f1 =     open("C:/Yasir/Thesis/4/FaceDetectionLatest/bin/Debug/Data/demoScoringData9.csv",   "a+")
reader = csv.reader(f1)
images = numpy.empty(len(onlyfiles), dtype=object)
for n in range(0, len(onlyfiles)):
    images[n] = cv2.imread( join(mypath,onlyfiles[n]) )
    # cv2.imshow(join(mypath,onlyfiles[n]),0)
    img = cv2.imread( join(mypath,onlyfiles[n]) )
    detector = FER()
    emotion = detector.detect_emotions(img)
    dict = emotion[0]
    emoList = dict['emotions']
    dict_writer = csv.DictWriter(f1, emoList)
    dict_writer.writerow(emoList)

I want to append the following values to a csv file which is already created. I mean the dict values should be appended to each row of csv except the header values like below.

{'angry': 0.15, 'disgust': 0.0, 'fear': 0.05, 'happy': 0.06, 'sad': 0.24, 'surprise': 0.02, 'neutral': 0.49}

I am also sharing the screenshot of my csv file screenshot

Please reformat the code above which wouldn't run as no indentations are present. — Sami Farhat
– Sami Farhat, Commented Feb 29, 2020 at 13:45
Hi, I have formatted the code and added the imports as well, please check, thank you — Yasir
– Yasir, Commented Feb 29, 2020 at 13:57
every time the for loop iterates, it gives the values something like {'angry': 0.15, 'disgust': 0.0, 'fear': 0.05, 'happy': 0.06, 'sad': 0.24, 'surprise': 0.02, 'neutral': 0.49} — Yasir
– Yasir, Commented Feb 29, 2020 at 15:26

Mark Tolonen · Accepted Answer · 2020-03-01 03:54:17Z

0

Here's a basic example of appending columns to an existing CSV:

data.csv (original)

col1,col2,col3
1,2,3
4,5,6
7,8,9

test.py

import csv

with open('data.csv',newline='') as fin:
    r = csv.DictReader(fin)
    lines = list(r)

with open('data.csv','w',newline='') as fout:
    # Create writer with existing column headers plus new column headers
    w = csv.DictWriter(fout,fieldnames=r.fieldnames + 'angry disgust fear happy sad surprise neutral'.split())
    w.writeheader()

    for line in lines:
        emolist = {'angry': 0.15, 'disgust': 0.0, 'fear': 0.05, 'happy': 0.06, 'sad': 0.24, 'surprise': 0.02, 'neutral': 0.49}
        line.update(emolist)
        w.writerow(line)

data.csv (final)

col1,col2,col3,angry,disgust,fear,happy,sad,surprise,neutral
1,2,3,0.15,0.0,0.05,0.06,0.24,0.02,0.49
4,5,6,0.15,0.0,0.05,0.06,0.24,0.02,0.49
7,8,9,0.15,0.0,0.05,0.06,0.24,0.02,0.49

edited Mar 1, 2020 at 3:54

answered Feb 29, 2020 at 22:46

Mark Tolonen

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3 Comments

Yasir Over a year ago

Hi, I appreciate your help but, please refer to my given code ; every time the for loop iterates, it produces emolist = {'angry': 0.15, 'disgust': 0.0, 'fear': 0.05, 'happy': 0.06, 'sad': 0.24, 'surprise': 0.02, 'neutral': 0.49} every time the values of angry , disgust , fear, happy , sad , surprise and neutral changes , now I don't want to update output.csv with input.csv , I want to update the output.csv with the emolist that is generated in every for loop iteration

Mark Tolonen Over a year ago

@Yasir Then replace the hard-coded emolist in my example with your code to generate the value. You didn't provide working code for that so just gave an example. If you want to read change the file in place, you'll have to read the whole file into memory, process the lines, then write the whole file out to the same filename. I'll update the example for writing to the same file.

Yasir Over a year ago

Thanks @Mark I tried replacing the emolist in your code with the emoList variable of my code but it makes the output file empty. Please update the code to take values from emoList variable and append it to the end of each row of my output csv file, Thanks a million

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