我真的是python新手，正在尋找一點(diǎn)幫助。我有一個(gè)包含當(dāng)前數(shù)據(jù)的文本文件：Tue Jun 25 **15** 336 0 0 0 0 0Tue Jun 25 **04** 12682 0 0 0 0 0 Tue Jun 25 **05** 12636 0 0 0 0 0Tue Jun 25 **06** 12450 0 0 0 0 0 Tue Jun 25 **07** 12640 0 0 0 0 0 我想遍歷每行并檢查是否 大于12。如果大于12，我想從中減去12，然后用新數(shù)字寫(xiě)回。下面是我到目前為止的代碼：infile = open("filelocation", "a+") #open the file with the data above and append / open itdef fun (line, infile): # define a function to to go to position 12 - 14 (which is where the date in bod is) and set it to an integer t = infile[12:14] p = int(t) if p > 12: # here is the logic to see if it is greater then 12 to subtract 12 and attempt to write back to the file. p = p - 12 k = str(p) infile.write(k) else: print p # probably not needed but i had it here for testing return# I was having an issue with going to the next line and found this code.for line in infile: print line, infile line = fun(line, infile.next()) breakinfile.close()主要問(wèn)題是它沒(méi)有遍歷每行或進(jìn)行更新。甚至可能有更好的方法來(lái)做我要嘗試做的事情，就是只是不了解或不了解某些功能的功能。任何幫助，將不勝感激！
2 回答
慕容3067478
TA貢獻(xiàn)1773條經(jīng)驗(yàn) 獲得超3個(gè)贊
inp = open("filelocation").readlines()
with open("filelocation", "w") as out:
for line in inp:
t = line[12:14]
p = int(t)
if p>12:
line = '{}{:02}{}'.format(line[:12], p-12, line[14:])
out.write(line)
拉丁的傳說(shuō)
TA貢獻(xiàn)1789條經(jīng)驗(yàn) 獲得超8個(gè)贊
for line in infile:
print line, infile
line = fun(line, infile.next())
break
break 離開(kāi)當(dāng)前循環(huán)，因此它將僅在第一行運(yùn)行，然后停止。
為什么您的fun函數(shù)在文件而不是行上運(yùn)行？您已經(jīng)有了該行，因此沒(méi)有理由再次閱讀它，并且我認(rèn)為像這樣寫(xiě)回它是一個(gè)壞主意。嘗試使其與以下功能簽名一起使用：
def fun(line):
# do things
return changed_line
為了處理文件，您可以使用with語(yǔ)句使此操作更簡(jiǎn)單，更簡(jiǎn)單：
with open("filelocation", "a+") as infile:
for line in infile:
line = fun(line)
# infile is closed here
對(duì)于輸出，要寫(xiě)回您正在讀取的相同文件是相當(dāng)困難的，因此，我建議您只打開(kāi)一個(gè)新的輸出文件：
with open(input_filename, "r") as input_file:
with open(output_filename, "w") as output_file:
for line in input_file:
output_file.write(fun(line))
或者，您可以讀入整個(gè)內(nèi)容，然后將其全部寫(xiě)回（但根據(jù)文件的大小，這可能會(huì)占用大量?jī)?nèi)存）：
output = ""
with open(filename, "r") as input_file:
for line in input_file:
output += fun(line)
with open(filename, "w") as output_file:
output_file.write(output)
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