Question

我正在抓取信息到文本文件，我正在尝试在顶部写日期。我有获取日期的方法，但不知道如何使用write函数放在顶部。以下是我工作的精简版。

import re
import urllib2
import json
from datetime import datetime
import time

now = datetime.now()
InputDate = now.strftime("%Y-%m-%d")
Today = now.strftime("%B %d")

header = ("Today").split()

newfile = open("File.txt", "w")

### Irrelevant Info Here ###

string = title"\n"+info+"\n"
#newfile.write(header)
newfile.write(string)
print title+" written to file"

newfile.close()

Answer 1

您无法在文件开头插入内容。您需要编写一个新文件，从您要插入的行开始，然后使用旧文件的内容完成。不像追加到最后，写入文件的开头实际上是非常低效的

此问题的关键是使用NamedTemporaryFile。完成构建后，然后将其重命名为旧文件。

代码：

def insert_timestamp_in_file(filename):
    with open(filename) as src, tempfile.NamedTemporaryFile(
            'w', dir=os.path.dirname(filename), delete=False) as dst:

        # Save the new first line
        dst.write(dt.datetime.now().strftime("%Y-%m-%d\n"))

        # Copy the rest of the file
        shutil.copyfileobj(src, dst)

    # remove old version
    os.unlink(filename)

    # rename new version
    os.rename(dst.name, filename)

测试代码：

import datetime as dt
import tempfile
import shutil

insert_timestamp_in_file("file1")

文件1

I am scraping info to a text file and am trying to write the date at
the top. I have the method to grab the date but have no clue how I can
use the write function to place at top. Been trying for 2 days and all.

结果：

2018-02-15
I am scraping info to a text file and am trying to write the date at
the top. I have the method to grab the date but have no clue how I can
use the write function to place at top. Been trying for 2 days and all.

Answer 2

只是为了给你提供想法

试试这个： -

import re
import urllib2
import json
from datetime import datetime
import time
now = datetime.now()
InputDate = now.strftime("%Y-%m-%d")
Today = now.strftime("%B %d")
#start writing from here
newfile = open("File.txt", "a")
newfile.write(InputDate+"\n")
newfile.write("hello Buddy")
newfile.close()

Answer 3

要将日期写入您想要放置的文件的“顶部”：

newfile.write(InputDate)
newfile.write(Today)

在您打开文件之后以及其他任何内容之前。

Answer 4

简单一个，如果您不将其称为def dosomething(): while selection == 1: ...... ......，那么它将抛出错误str

我已经刷新了代码以便更精确有效地使用..

TypeError: write() argument must be str, not list

结果将是：

import re
from datetime import datetime
import time

now = datetime.now()
InputDate = now.strftime("%B"+" "+"%Y-%m-%d")
newfile = open("File.txt", "a")
string = "Hi trying to add a datetime at the top of the file"+"\n"
newfile.write(str(InputDate+"\n"))
newfile.write(string)
newfile.close()

Python - 在正在编写的文件顶部添加行

4 个答案:

代码：

测试代码：

文件1

结果：