如何在線將char寫入文件
[英]How to write char on line into file
問題描述
我有一個大文本文件，
zhang
zhipeng
peng
我想讓N行之前或左行將str “-”寫入文本文件。
zhang
--zhipeng
peng
我不想將所有文件讀到內存，因為文件太大。 有點類似標記文件的某些行。
回答
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <title>/opt/work/users/zhanghzipeng/baidu_baike/baike/utils/text_helper.py.html</title> <meta name="Generator" content="Vim/7.2"> <meta http-equiv="content-type" content="text/html; charset=UTF-8"> </head> <body bgcolor="#000000" text="#ffffff"><font face="monospace"> <font color="#ffff00"> 1 </font><font color="#00ffff"># -*- coding:utf-8 -*-</font><br> <font color="#ffff00"> 2 </font><br> <font color="#ffff00"> 3 </font><br> <font color="#ffff00"> 4 </font><font color="#00ffff"># @version: 1.0</font><br> <font color="#ffff00"> 5 </font><font color="#00ffff"># @author: Zhipeng Zhang</font><br> <font color="#ffff00"> 6 </font><font color="#00ffff"># @date: '2015/5/28'</font><br> <font color="#ffff00"> 7 </font><font color="#ff40ff">import</font> os<br> <font color="#ffff00"> 8 </font><br> <font color="#ffff00"> 9 </font><font color="#ff40ff">import</font> fileinput<br> <font color="#ffff00">10 </font><br> <font color="#ffff00">11 </font><br> <font color="#ffff00">12 </font><font color="#ffff00">def</font> <font color="#00ffff">rewrite_line</font>(filename, lineno, text, left=True, right=False):<br> <font color="#ffff00">13 </font> f = fileinput.input(filename, inplace=1)<br> <font color="#ffff00">14 </font> <font color="#ffff00">for</font> line <font color="#ffff00">in</font> f:<br> <font color="#ffff00">15 </font> line_text = line.replace("<font color="#ff40ff">\\r\\n</font>", "").replace("<font color="#ff40ff">\\n</font>", "")<br> <font color="#ffff00">16 </font> <font color="#ffff00">if</font> f.lineno() == lineno:<br> <font color="#ffff00">17 </font> <font color="#ffff00">if</font> left:<br> <font color="#ffff00">18 </font> <font color="#ffff00">print</font> text + line_text<br> <font color="#ffff00">19 </font> <font color="#ffff00">elif</font> right:<br> <font color="#ffff00">20 </font> <font color="#ffff00">print</font> line_text + text<br> <font color="#ffff00">21 </font> <font color="#ffff00">else</font>:<br> <font color="#ffff00">22 </font> <font color="#ffff00">print</font> text<br> <font color="#ffff00">23 </font> <font color="#ffff00">else</font>:<br> <font color="#ffff00">24 </font> <font color="#ffff00">print</font> line_text<br> <font color="#ffff00">25 </font> f.close()<br> <font color="#ffff00">26 </font><br> <font color="#ffff00">27 </font><font color="#ffff00">def</font> <font color="#00ffff">cat</font>(filename):<br> <font color="#ffff00">28 </font> <font color="#ffff00">with</font> file(filename) <font color="#ff40ff">as</font> f:<br> <font color="#ffff00">29 </font> <font color="#ffff00">print</font> f.read()<br> <font color="#ffff00">30 </font> os.remove(filename)<br> <font color="#ffff00">31 </font> <font color="#ffff00">with</font> file(filename, "<font color="#ffff00">w</font>")<font color="#ff40ff">as</font> f:<br> <font color="#ffff00">32 </font> f.write("<font color="#ffff00">a</font><font color="#ff40ff">\\n</font><font color="#ffff00">b</font><font color="#ff40ff">\\n</font><font color="#ffff00">c</font>")<br> <font color="#ffff00">33 </font><br> <font color="#ffff00">34 </font><font color="#ffff00">def</font> <font color="#00ffff">test</font>():<br> <font color="#ffff00">35 </font> filename = "<font color="#ffff00">rewrite.test</font>"<br> <font color="#ffff00">36 </font> <font color="#ffff00">with</font> file(filename, "<font color="#ffff00">w</font>")<font color="#ff40ff">as</font> f:<br> <font color="#ffff00">37 </font> f.write("<font color="#ffff00">a</font><font color="#ff40ff">\\n</font><font color="#ffff00">b</font><font color="#ff40ff">\\n</font><font color="#ffff00">c</font>")<br> <font color="#ffff00">38 </font><br> <font color="#ffff00">39 </font> <font color="#ffff00">print</font> "<font color="#ffff00">new file:</font>" + filename<br> <font color="#ffff00">40 </font> <font color="#ffff00">print</font> "<font color="#ffff00">file content: a</font><font color="#ff40ff">\\n</font><font color="#ffff00">b</font><font color="#ff40ff">\\n</font><font color="#ffff00">c</font>"<br> <font color="#ffff00">41 </font><br> <font color="#ffff00">42 </font> <font color="#ffff00">print</font> "<font color="#ffff00">--------start test---------</font>"<br> <font color="#ffff00">43 </font><br> <font color="#ffff00">44 </font> <font color="#ffff00">print</font> filename, "<font color="#ffff00">line:</font>", 2, "<font color="#ffff00">left add # --> #b?</font>"<br> <font color="#ffff00">45 </font> rewrite_line(filename, 2, "<font color="#ffff00">#</font>", left=True)<br> <font color="#ffff00">46 </font> cat(filename)<br> <font color="#ffff00">47 </font><br> <font color="#ffff00">48 </font><br> <font color="#ffff00">49 </font> <font color="#ffff00">print</font> filename, "<font color="#ffff00">line:</font>", 2, "<font color="#ffff00">right add #END --> b#END?</font>"<br> <font color="#ffff00">50 </font> rewrite_line(filename, 2, "<font color="#ffff00">#END</font>", left=False, right=True)<br> <font color="#ffff00">51 </font> cat(filename)<br> <font color="#ffff00">52 </font><br> <font color="#ffff00">53 </font> <font color="#ffff00">print</font> filename, "<font color="#ffff00">line:</font>", 1, "<font color="#ffff00"> rewrite a --> zhipeng?</font>"<br> <font color="#ffff00">54 </font> rewrite_line(filename, 1, "<font color="#ffff00">zhipeng</font>", left=False, right=False)<br> <font color="#ffff00">55 </font> cat(filename)<br> <font color="#ffff00">56 </font><br> <font color="#ffff00">57 </font> os.remove(filename)<br> <font color="#ffff00">58 </font><br> <font color="#ffff00">59 </font><br> <font color="#ffff00">60 </font><font color="#ffff00">if</font> __name__ == "<font color="#ffff00">__main__</font>":<br> <font color="#ffff00">61 </font> test()<br> </font></body> </html>
1 個解決方案
解決方案1
0 已采納 2015-05-28 06:19:46
# implement
def mark(ifn, ofn, linenum):
with open(ifn, "rt") as ifile:
with open(ofn, "wt") as ofile:
n = 0
for line in ifile.readlines():
n = n + 1
if n == linenum:
ofile.write("---")
ofile.write(line)
# execute
mark("a.txt", "b.txt", 4)
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