读取python中的最后一行后，返回文件的开头

Question

I want to read a file line by line, but after reading the last line it should return to the beginning of the file.

Here is my code:

def readLabels(self, n):
    resline = np.empty([0,2])
    for i in range(0,n):
        line = (self.f2.readline()).split(',')
        line = [x for x in line if is_number(x)]
        line = [float(s) for s in line]
        line = np.asarray(line)
        resline = np.concatenate((resline, [line]),axis=0)
    return resline

This function returns n lines of the file as a batch. However, it should continuously return to the beginning of the file, so that I can read batches over and over again. So how can I make readline return to the beginning?

Thank you for your time!

Answer 1

You can probably try self.f2.seek(0) after you read it the first time. This will set the offset position to 0.

Answer 2

You have to seek the beginning of the file.

So in your case I think the file is self.f2 , thus you have to use:

self.f2.seek(0)

Answer 3

you should check what readline() returns. If it returns empty string, then you can go back to the beginning of the file.

def readLabels(self, n):
    resline = np.empty([0,2])
    for i in range(0,n):
        line = self.f2.readline()
        if not line:
            # back to top
            self.f2.seek(0)
            # read again
            line = self.f2.readline()
        line = line.split(',')
        line = [x for x in line if is_number(x)]
        line = [float(s) for s in line]
        line = np.asarray(line)
        resline = np.concatenate((resline, [line]),axis=0)
    return resline