Python-如何在读取csv文件时读取前几行？

Question

I want to read rows in excel table but when I want, during reading process, I would like to stop reading forward and I want to read previous lines (backward reading)? How can I go previous rows again?

import csv

file = open('ff.csv2', 'rb')
reader = csv.reader(file)

for row in reader:
    print row

Answer 1

You could always store the lines in a list and then access each line using the index.

import csv
file = open('ff.csv2', 'r')

def somereason(line):
    # some logic to decide if stop reading by returning True
    return False  # keep on reading

for row in csv.reader(file):
    if somereason(line):
        break

    lines.append(line)

# visit the stored lines in reverse
for row in reversed(lines):
   print(row)