python - 在Python中使用seek()

Question

我正在努力读取特定的动态心电图数据(.ecg 文件)并将用户指定的特定数据复制到新文件中。基本上，我只想将必要的数据读入内存。有没有办法使用 .seek() 只从(开始，结束)读取数据字节？

start = args.packet_start
end = args.packet_end

try:

    print("Beginning copying of holter data...")

    # Output the specific holter data
    output_file = open("copied_holter.ecg", 'w')

    # Read part of holter file into memory
    holter = open(args.filename, 'rb')
    data = holter.seek()

# Parse through holter data and copy to file
    for index in range(start, end+1):
    data_list = data[index]
    output_file.write(data_list)

    # Close the file streams
    holter.close()
    output_file.close()  

except Exception as e:
    print(e)
    print("Exiting program, due to exception.")
    exit(1)

print "Finished data copying operations!"

Answer 1

seek 会将指针移动到指定位置，而不返回数据。 read 将返回指定的字节数。此外，在处理文件或类似文件的对象时，您应该使用 with 语句。

with open(args.filename, 'rb') as holter, open("copied_holter.ecg", 'w') as output_file:
    holter.seek(start)
    data = holter.read(end-start)
    output_file.write(data)