逐行读取文件，而不是将文件读取到内存 [英] Read a file line-by-line instead of read file into memory

问题描述

我在逐行读取文件时遇到了麻烦，而不是将文件读取到内存中.截至目前，我正在将文件读入内存，并且可以正常运行.但是，如果我尝试逐行读取文件，则在键入"print(B)"时只能得到零.我的问题是，有人在python中逐行读取文件吗?我的代码如下:

I´m having some trouble with reading a file line-by-line, instead of reading the the file into memory. As of right now, I'm reading the file into memory, and it works perfect. However, If i try to read the file line-by-line, I only get zero when I type 'print(B)'. My question is, does anyone have a good command for reading the file line-by-line in python? My code looks like this:

def read(filename):

    with open(filename, 'r') as f: #open the file

        for line in f:

            A = sum(float(line) for line in f)

    with open(filename, 'r') as f:

            B = sum(float(line)**2 for line in f)

            print(B)

read('file.txt')

推荐答案

这对您来说合适吗?

with open(filename, 'r') as f:
    data = f.readlines()

A = sum(float(line) for line in data)
B = sum(float(line)**2 for line in data)

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