描述

Retrieving a Line at Random from a File of Unknown Size 读取未知大小文件的随机一行

问题 Problem

有文件，不清楚大小(但是可能非常大)，需要忽略文件本身，只读取数据的随机一行。

解决 Solution

We do need to read the whole file, but we don't have to read it all at once: 需要读取文件的全部数据,但是不是一次全部读出:

import random

def randomLine(file_object):
    "顺序读取文件内容,取文件的随机的一行"
    lineNum = 0
    selected_line = ''

    while 1:
        aLine = file_object.readline(  )
        if not aLine: break
        lineNum = lineNum + 1
        # How likely is it that this is the last line of the file?
        if random.uniform(0,lineNum)<1:  #译注: 这里是随机的吗?
            selected_line = aLine
    file_object.close(  )
    return selected_line

讨论 Discussion

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PyCkBk-4-6

描述

问题 Problem

解决 Solution

讨论 Discussion

参考 See Also