CSV Files: reader और writer

Roll,Name,Class,Marks
1,Asha,XII-A,91
2,Ravi,XII-B,67
3,Neha,XII-A,85

import csv
rows = [['Roll', 'Name', 'Class', 'Marks'],
        [1, 'Asha', 'XII-A', 91],
        [2, 'Ravi', 'XII-B', 67],
        [3, 'Neha', 'XII-A', 85]]
with open('result.csv', 'w', newline='') as f:
    w = csv.writer(f)
    w.writerow(rows[0])          # header
    w.writerows(rows[1:])        # many rows at once
with open('result.csv') as f:
    print(f.read(), end='')      # it is just text

import csv
with open('result.csv', newline='') as f:
    r = csv.reader(f)
    for row in r:
        print(row)             # every row is a LIST of strings

import csv
def add_student():
    with open('result.csv', 'a', newline='') as f:
        csv.writer(f).writerow([4, 'Kabir', 'XII-B', 74])
add_student()
with open('result.csv', newline='') as f:
    data = list(csv.reader(f))
print('Rows (with header):', len(data), '| last:', data[-1])

import csv
def toppers(limit):
    with open('result.csv', newline='') as f:
        r = csv.reader(f)
        next(r)                      # skip the header row
        count = 0
        for roll, name, cls, marks in r:
            if int(marks) > limit:   # convert text to number
                print(name, marks)
                count += 1
    print('Count:', count)
toppers(80)

import csv
def search(name):
    with open('result.csv', newline='') as f:
        for row in csv.reader(f):
            if row[1].lower() == name.lower():
                return row
    return None
print(search('neha'))
print(search('Zoya'))

import csv
# copy only XII-B students into a new CSV
with open('result.csv', newline='') as src, open('xiib.csv', 'w', newline='') as dst:
    r = csv.reader(src)
    w = csv.writer(dst)
    w.writerow(next(r))                 # copy header
    for row in r:
        if row[2] == 'XII-B':
            w.writerow(row)
with open('xiib.csv') as f:
    print(f.read(), end='')

import csv
def class_average(section):
    total = n = 0
    with open('result.csv', newline='') as f:
        for row in csv.DictReader(f):          # each row is a dict
            if row['Class'] == section:
                total += int(row['Marks'])
                n += 1
    return round(total / n, 2) if n else 0
print('XII-A average:', class_average('XII-A'))
print('XII-B average:', class_average('XII-B'))

import csv
with open('items.csv', 'w', newline='') as f:
    w = csv.writer(f, delimiter=';')            # semicolon-separated
    w.writerow(['Item', 'Price'])
    w.writerow(['Pen, blue', 10])              # comma inside value is safe
with open('items.csv') as f:
    print(f.read(), end='')
with open('items.csv', newline='') as f:
    print(list(csv.reader(f, delimiter=';')))