写在CSV文件的最上面一行 [英] Writing on the topmost row of a CSV file

问题描述

我有这个sample.csv档案：

I have this sample.csv file:

a   1   apple
b   2   banana
c   3   cranberry
d   4   durian
e   5   eggplant

并具有以下代码：

samplefile = open(sample.csv,'rb')
rows = samplefile .readlines()
outputfile = open(output.csv,'wb')
wr = csv.writer(outputfile)
for row in rows:
     wr.writerow(row)

我想要的是在for循环的某个时刻写入outputfile的第一行，即outputfile可能已经有条目。 / p>

What I wanted to to is write on the first row of outputfile at some point during the for loop, i.e. when outputfile may already have entries.

推荐答案

如果要添加到文件末尾（添加到文件末尾）：

If you want to add to the end of the file(append to it):

with open("sample.csv", "a") as fp:
     fp.write("new text")

如果要覆盖文件：

with open("sample.csv", "w") as fp:
     fp.write("new text")

如果您要从文件中删除一行：

import fileinput
import sys

for line_number, line in enumerate(fileinput.input('myFile', inplace=1)):
  if line_number == 0:  #first line
    continue
  else:
    sys.stdout.write(line)

如果要添加新的第一行（在现有行之前）：

If you want to add a new first line(before the existing one):

with open("sample.csv", "r+") as fp:
     existing=fp.read()
     fp.seek(0) #point to first line
     fp.write("new text"+existing) # add a line above the previously exiting first line

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