python按行读文件

方法一：readline函数

with open(file_path, 'r') as file:
    line = file.readline()
    while line:
        print(line)
        line = file.readline()

方法二：readlines函数

with open(file_path, 'r') as file:
    lines = file.readlines()
    for line in lines:
        print(line)

方法三：for循环直接读取

在Python 2.2以后，我们可以直接对一个file对象使用for循环读每行数据：

with open(file_path, 'r') as file:
    for l in file:
        print(l)

而在Python 2.1里，你只能用xreadlines迭代器来实现

方法四：用fileinput模块

import fileinput
for line in fileinput.input("sample.txt"):
    print(line)

例如用两种方法筛选文件中含有关键字$GNGLLd的行并存储到新的文件中：

# 方法一
def extract_lines_with_keyword(file_path, keyword):
    extracted_lines = []
    with open(file_path, 'r') as file:
        lines = file.readlines()
        for line in lines:
            if keyword in line:
                extracted_lines.append(line[line.index(keyword):])
    return extracted_lines

file_path = r'C:\Users\KONG\Desktop\922.nma'  # 输入文件路径
keyword = '$GNGLL'
extracted_lines = extract_lines_with_keyword(file_path, keyword)

output_file_path = r'C:\Users\KONG\Desktop\ot.nma'  # 输出文件路径
with open(output_file_path, 'w') as output_file:
    for line in extracted_lines:
        output_file.write(line)
        
# 方法二
def extract_lines_with_keyword(file_path, keyword):
    extracted_lines = []
    with open(file_path, 'r') as file:
        for l in file:
            if keyword in l:
                extracted_lines.append(l[l.index(keyword):])
    return extracted_lines

file_path = r'C:\Users\KONG\Desktop\922.nma'  # 替换为你的输入文件路径
keyword = '$GNGLL'
extracted_lines = extract_lines_with_keyword(file_path, keyword)

output_file_path = r'C:\Users\KONG\Desktop\op.nma'  # 替换为你想要输出的文件路径
with open(output_file_path, 'w') as output_file:
    for line in extracted_lines:
        output_file.write(line)