从 Python 2.7 中的 csv 文件中删除最后一行/页脚

Question

import csv
import operator
import os
import sys

with open('test.csv', 'r') as cvsfile:
    f = csv.reader(csvfile, delimiter=',')
    for line in f:
        line = [line:-1]
        print (line)

======

尝试了上述我试图在排序之前从 csv 文件中删除最后一行。 我可以使用 next() 命令去除页眉，但无法去除页脚。

Answer 1

要删除第一行/最后一行，您可以将 csv.reader 转换为列表，然后在其上使用[1:-1] 。 例如：

import csv

with open('test.csv', 'r') as csvfile:
    f = csv.reader(csvfile, delimiter=',')
    
    for line in list(f)[1:-1]:  # [1:-1] to strip first/last line from csv
        print (line)

Answer 2

如果您正在处理一个大数据集， list(f)[1:-1]将立即将整个集合加载到内存中，然后制作该列表的副本，而不包含原始列表的第一个和最后一个元素。 要继续使用生成器，以便一次只将一行加载到内存中，

import csv
import operator
import os
import sys

curr = None
next_line = None
with open('test.csv', 'r') as cvsfile:
    f = csv.reader(csvfile, delimiter=',')
    next(f) # remove first line
    try:
        curr = next(f)
        next_line = next(f)
        while True:
            print(curr)
            curr = next_line
            next_line = next(f) 
    except StopIteration: 
        pass