使用Python解析大型.csv文件行

Question

A large .csv file has a typical row with approx 3000 data elements separated by commas. Approximately 50% of this data is fluff(non-value added data) and can be removed. How can I remove this fluff with multiple string removals? I am new to Python.

I can read the data. I am unable to change the data. Variable x in the code below would be the changed string by row.

with open('som_w.csv','r+') as file:
    reader = csv.reader(file, delimiter=',')
    for i, row in enumerate(reader):
        print(row)
        print(i+1)

writer = csv.writer(file, delimiter=',')
for row in writer:
    x = re.sub(r'<.*?>',"",writer)
    print(x)

file.close()

The current error is the csv.writer is not iterable. I believe I'm heading down the wrong path.

Answer 1

Take a look at comments. I think it should help.

with open('som_w.csv','r+') as file:
    reader = csv.reader(file, delimiter=',')
    for i, row in enumerate(reader):
        print(row)
        print(i+1)

writer = csv.writer(file, delimiter=',') # isn't `file` out of scope?
for row in writer:
    x = re.sub(r'<.*?>',"",writer)
    print(x)

file.close() # while using `with`, it's unnecessary to close file.

Answer 2

Look at this post , there is an example for a function which replace all lines with help of regular expression.

Then try this:

import fileinput
import sys

def replaceAll(file, searchExp, replaceExp):
    with fileinput.input(file) as f:
        for line in f:
            if searchExp in line:
                line = line.replace(searchExp, replaceExp)
            sys.stdout.write(line)

replaceAll('som_w.csv', r'<.*?>', "")